Self climbing tower crane and method

Abstract

A self-climbing tower crane (1) which comprises tower segments (3, 4) which are configured to be stacked onto one another from below in order to erect a crane tower. The crane further has a crane tower lifting unit (10) which is configured to stepwise lift the crane tower from below. The crane is further provided with a slewable jib (100) unit which comprises a crane housing (110), a lifting jib (120), and a counter jib (130) comprising a counter ballast (132) or counter cable (1107), wherein the lifting jib and counter jib are both pivotable between a horizontal position and a substantially vertical position and pivotably connected to the crane housing.

Description

[0001] SELF CLIMBING TOWER CRANE

[0002] The present invention relates to the field of self-climbing tower cranes. In particular, the invention is envisaged for the use of such a tower crane in the field of wind turbines, e.g. when assembling a wind turbine, installing or de-installing a wind turbine rotor blade, generator, gearbox, etc.

[0003] In the field of wind turbine installation and maintenance it is known to make use of a selfclimbing tower crane. Generally such a crane comprises:

[0004] - a crane base configured to the placed on the support at the hoisting site,

[0005] - a crane tower to be erected on the crane base and to be composed of tower segments that are to be stacked one-by-one onto one another,

[0006] - a crane tower lifting unit configured to perform a lifting action in the process of erecting the tower crane,

[0007] - a slewable jib unit configured to be mounted on top of the crane tower.

[0008] For example, the Liebherr 1000 EC-B 125 Litronic Tower Crane has been used to erect a wind turbine having a hub height of 149 m and a rotor diameter of 115m. This crane has a 31.50m jib and provides a hook height of 164m, with a hoisting capacity of 100 tonnes.

[0009] A key factor in the deployment of cranes at the location of a wind turbine is the footprint. For onshore wind turbines, often a so-called hardstand is prepared close to the foundation of the wind turbine to allow for stable placement of the tower crane. Sometimes the crane base is secured directly to the (concrete) foundation of the wind turbine.

[0010] The Liebherr crane is erected by a method that starts with an initiation phase wherein a sizable auxiliary crawler crane is used to assemble the tower crane to an initial hook height of 39 m. From this point the self-climbing tower crane assembly phase takes place, wherein the tower crane is further erected by stacking tower segments one-by-one on top of one another to lengthen the crane tower under the jib unit. Herein the crane tower lifting unit is located directly underneath the jib unit and performs a lifting action each time a tower segment has been stacked. The crane tower segments are generally embodied as latticed steel segments having main chords at the corners with a square horizontal cross-section, in the case of the Liebherr crane of 3.40m x 3.40m with a length of 5.80m. The jib of the Liebherr crane is of the non-luffing type, with a trolley that travels over the horizontal jib. The crane hoisting cable(s) depend from the trolley and extend to one or more winches of the slewable jib unit. The Liebherr jib has a counter jib section provided with a counter ballast. This known crane has at least one external stabiliser device configured to horizontally connect the crane tower to the wind turbine mast.

[0011] Another known self-climbing tower crane for use in the field of wind turbine installation is disclosed in EP3434639. Herein the crane tower lifting unit is mounted on the crane base and remains at said location. In practice, the initiation phase of this known tower crane involves the use of one or more sizable auxiliary cranes to assemble the tower crane to an initial hook height. From this point the tower crane assembly phase takes place, wherein the crane tower is erected by stacking tower segments one-by-one from below to lengthen the crane tower under the jib unit. Herein the crane tower lifting unit performs a lifting action each time a tower segment has been stacked underneath the already assembled part of the tower crane. This known crane tower has multiple external stabiliser devices, each configured to horizontally connect the crane tower to the wind turbine mast.

[0012] During hoisting operations, the very tall and vertically oriented crane tower is subject to significant loads thereon, such as bending stresses and torsional loads, e.g. when hoisting a wind turbine blade or nacelle. In another known self-climbing tower crane, disclosed in WO2023118352, the crane tower comprises of two different tower segment types. Lower tower segments are embodied as latticed steel segments and upper tower segments embodied as tubular girder segments. The tubular girder segments are less likely to deform under the bending stresses and torsional loads.

[0013] Another known self-climbing tower crane for use in the field of wind turbine installation is disclosed in WO2018050278. The crane described herein is provided with a crane tower lifting unit which is arranged at the top of the crane tower and is used to erect the crane tower by stacking tower segments one-by-one from above. The crane further comprises a main boom and a counter boom, which are both upwardly and downwardly pivotable, and the main boom and counter boom are each provided with a hoisting assembly. The hoisting assembly of the counter boom is used to lift a counter ballast, which makes it easier to change the counter weight during lifting operations. The counter boom is further used to lift and install tower segments from above into the crane tower lifting unit.

[0014] The invention aims to provide an improved self-climbing tower crane, e.g. in view of stabilising the tower crane during lifting operations and during the assembly of the tower crane itself. The invention also seeks to improve the absorbing of loads acting on the crane tower.

[0015] The invention also seeks to reduce space required at the hoisting site, time / or efforts for assembly of the tower crane at the hoisting site, transportation of the components of the tower crane, etc.

[0016] The invention also seeks to provide a tower crane which is effective for use in the offshore wind industry.

[0017] The present invention provides a method for erecting a self-climbing tower crane according to claim 1 in order to achieve one or more of the objectives above.

[0018] The tower crane is, in practical embodiments, positioned and erected close to and along the mast of the wind turbine during the installation of a wind turbine blade, e.g. for replacement of a damaged blade by a new blade. Due to the dimensions of the wind turbine blade and the position of the tower crane, the lifting point of the wind turbine blade is located at a substantial horizontal distance away from the tower mast, this creates a large moment and thus high stress and loads in the crane tower. The counter jib, in cooperation with the counter ballast thereon or in cooperation with the counter cable and associated counter winch, creates an opposite moment which reduces the stress and loads on the crane tower. This allows the tower segments to be of a lighter weight and / or reduces the loads on any stabiliser device connecting the crane tower to the tower mast of the wind turbine.

[0019] The method of claim 1 , wherein the lifting jib and the counter jib are both pivoted to a substantial vertical upward orientation during the assembly of the crane tower, increases the stability of the crane tower during the assembly thereof, decreases the required space at the hoisting site, and may allow for easier transportation of the jib unit. In embodiments, it may allow for a permanent attachment of a counter ballast to the counter jib prior to the lengthening of the crane tower (avoiding the need for a hoist associated with the counter ballast). If a counter cable and associated counter winch is used, the need for a counter ballast is not present. In order to perform a lifting operation with the tower crane, e.g. of a wind turbine blade, the jibs can be pivoted into a substantially horizontal orientation or intermediate positions, which increases the reach and stability of the crane. Furthermore, the vertical orientation of the jibs during the assembly of the crane tower allows for more positional freedom of the crane tower relative to a wind turbine mast, because the jibs will then not interfere with the wind turbine mast. The method wherein the crane tower is assembled by stacking the tower segments one-by- one from below also saves a lot of weight at the top of the tower since the crane tower lifting unit is arranged at a low position, e.g. on the ground or close to the foot of and not at the top of the crane tower. This results in a more stable tower crane and results in much lower torque in the crane tower due to slewing of the jib unit or due to wind loads acting on the crane.

[0020] The pivotable counter jib allows the counter ballast, preferably arranged at the outer end thereof, to act as a variable counter ballast by suitable pivoting of the jib. Depending on the lifting operation the counter jib can pivoted between the horizontal orientation, the substantially vertical orientation, and intermediate positions, this changes the horizontal distance between the counter ballast and the crane tower. Alternatively, by operating the counter winch the counter cable can apply a variable vertical downward force on the outer end of the counter jib, thus also acting as a variable counter ballast. The present invention thus allows an easier and more efficient adaptability to different lifting operations of the crane and / or during a lifting operation.

[0021] In an embodiment, the first and second luffing assemblies are independently operable from each other. In another embodiment, the luffing assemblies operate in synchrony with one another, e.g. so that the jibs always have the same luffing angle relative to the vertical.

[0022] In practical embodiments, when the tower crane is used for activities related to a wind turbine, the support may be present adjacent or on a lower end of a wind turbine mast. For example, the support can then be a wind turbine foundation, e.g. of an offshore wind turbine , e.g. a bottom fixed foundation such as a monopile, a jacket, a tripod, etc or on a floating foundation of a wind turbine. In another embodiment, the support for the tower crane is formed by a vessel, e.g. a semi-submersible vessel or a jack-up vessel. For example, a jack-up vessel is provided with a mobile cantilever on which the tower crane is mounted. For example, such a jack-up vessel is positioned with its jack-up legs placed on the seabed in proximity of an offshore wind turbine and the cantilever with the tower crane thereon is then moved relative to the hull of the jack-up vessel so that the tower crane is brought closer to the wind turbine, e.g. allowing for the use of stabiliser devices for the crane tower as discussed herein.

[0023] In an embodiment, before the crane tower assembly phase, the method further comprises the followings steps:

[0024] - placing the crane base on the support;

[0025] - mounting the crane tower lifting unit on the crane base;

[0026] - placing the slewable lifting jib unit on the crane tower lifting unit. In an embodiment, the crane tower lifting unit is already mounted on the crane base prior to the placing of the crane base on the support. Optionally, e.g. for an offshore application, the slewable lifting jib unit is already placed in an installation position on the crane base at or near the crane tower lifting unit.

[0027] In an embodiment, the crane tower lifting unit comprises a vertical lifting column, e.g. mounted on the crane base, wherein, optionally the vertical lifting column is pivotable between a horizontal position and a vertical position relative to the crane base. The crane tower lifting unit further comprises a lifting tool which is movable along the vertical lifting column for use during the crane tower assembly phase, wherein the lifting tool engages a tower segment at the lower end thereof, preferably at the connector members thereof, and lifts the already assembled part of the crane tower to such a height that a further tower segment can be placed under the crane tower. The crane tower is subsequently connected to the further segment, e.g. the crane tower is subsequently lowered and connected to the further tower segment, preferably using the connectors of the tower segments.

[0028] In an embodiment, the crane base is configured to store the tower segments thereon at respective storage positions, preferably in a vertical orientation, and the crane base is provided with a tower segment transfer trolley, wherein the tower segment transfer trolley is configured to engage a tower segment at a respective storage position and to move the tower segment, preferably in a vertical orientation, to an installation position where the tower segment is positioned underneath and aligned with the lifted already assembled part of the crane tower.

[0029] In an embodiment, the tower segment transfer trolley is provided with mounting members, e.g. configured to cooperate with connectors of a tower segment, wherein a tower segment is to be connected to the mounting members of the tower segment transfer trolley, e.g. by an auxiliary crane or by operation of the trolley, and the tower segment transfer trolley- once the already assembled part of the crane tower has been lifted - is moved from a storage position to the installation position.

[0030] In an embodiment, during the step of placing the slewable lifting jib unit on the crane tower lifting unit, the slewable jib unit is placed on the crane tower lifting unit while both the slewable jib unit and the vertical lifting column are horizontally oriented, and wherein the interconnected slewable lifting unit and the vertical lifting column are pivoted from a horizontal orientation to a vertical orientation. In an embodiment, the crane tower comprises of lower and upper tower segments, each lower tower segment comprises an inner lower tower segment and an outer lower tower segment, the inner lower tower segment having a longitudinal axis, wherein the outer lower tower segment telescopically envelopes the inner lower tower segment so as to be movable along the longitudinal axis of the inner lower tower segment between a retracted and an extended position, wherein the method further comprises the following steps:

[0031] - connecting the upper portion of the outer lower tower segment to the lifted crane tower, wherein the outer lower tower segment is in the retracted position;

[0032] - engaging the lifting tool to the lower portion of the outer lower tower segment;

[0033] - moving the outer lower tower segment from the retracted position to the extended position;

[0034] - locking the outer lower tower segment relative to the inner lower tower segment.

[0035] In an embodiment, the crane tower is provided with one or more stabiliser devices which are configured to be connect the crane tower to a wind turbine mast. The stabiliser devices are configured to increase the stability of the tower crane. The stabiliser devices are configured to clamp onto the wind turbine mast, e.g. by clamping members squeezed onto the mast and / or by one or more clamping members encircling the wind turbine mast, e.g. as a sling. The stabiliser device is provided with a crane tower portion and a clamping portion, wherein - during the crane tower assembly phase - the one or more stabiliser devices are installed on the crane tower and engage the wind turbine mast by means of the clamping portion.

[0036] In an embodiment, the clamping portion of the one or more stabiliser devices is pivotably connected to the crane tower portion, the clamping portion being configured to pivot between a horizontal operational position and a vertical mounting position, wherein the installation of the one or more stabiliser devices comprises the following steps:

[0037] - placing the stabiliser device between the crane tower and the external tall structure, e.g. the wind turbine mast, wherein the clamping portion of the stabiliser device is in the vertical mounting position;

[0038] - connecting the crane tower portion of the stabiliser device to the crane tower;

[0039] - pivoting the clamping portion from the vertical mounting position to the horizontal operational position;

[0040] - engaging the external tall structure, e.g. the wind turbine mast, with the clamping portion. In an embodiment, the tower segments, at least at the upper portion of the crane tower, are provided with at least one guide rail extending along the height of the upper tower segment, and optionally also the lower tower segments, such that the guide rails of interconnected tower segments form a substantially continuous vertical guide rail. The one or more stabiliser devices, e.g. the tower crane portion thereof, are mounted on the guide rail(s) and are moved along the height of the tower crane, preferably - before being moved along the height of the tower crane - the stabiliser device disengages from the wind turbine mast and reengages with the wind turbine mast when the stabiliser device is in the correct position. For example, this way one or more clamping portions of the stabiliser device(s) do not damage the paint of the wind turbine mast.

[0041] In an embodiment, the tower crane is provided with one or more stabiliser hoist devices, e.g. one or more winches, which is / are arranged on the crane tower, preferably at a top end thereof, and configured and operated to hoist the one or more stabiliser device along the crane tower, e.g. while the one or more stabiliser devices are engaged with the track.

[0042] In an embodiment, the crane tower lifting unit is provided with one or more stabiliser devices which are configured to be connect the crane tower lifting unit to a wind turbine mast. The stabiliser devices are configured to increase the stability of the crane tower lifting unit. The stabiliser devices are configured to clamp onto the wind turbine mast, e.g. by clamping members squeezed onto the mast and / or by one or more clamping members encircling the wind turbine mast, e.g. as a sling.

[0043] The present invention also relates to a method for simultaneously erecting a tower crane on a support and constructing a wind turbine mast at a hoisting site. The wind turbine mast comprises multiple segments which are configured to be stacked onto one another from above. During the crane tower assembly phase - once the slewable lifting unit is sufficiently high - the slewable lifting unit is used to lift a wind turbine mast segment onto the top of the already installed wind turbine mast segments, e.g. wherein both the counter jib and the lifting jib are moved from the substantially upward vertical orientation to the horizontal orientation.

[0044] In an alternative embodiment of the method and tower crane, an upper crane housing section comprises a base and a vertical housing column, the vertical housing column having a lower end and a top end, wherein at the top end the vertical housing column is provided with a luffing sheave assembly, and wherein the base and the vertical housing column are configured to be connected to each other, wherein the lifting jib comprises a first and second lifting jib section, each section having an inner and an outer end, wherein the inner end of the first section is configured to be pivotally mounted to the upper crane housing section base around a lifting jib pivot axis, and wherein the first and second lifting jib sections are hingedly connected at their outer end and inner end respectively, such that first and second lifting jib sections can pivot with respect to each other between a folded and an extended position, and wherein the outer end of the second lifting jib section is configured to receive a boom head thereon, wherein the counter jib comprises a first and second counter jib section, each section having an inner and an outer end, wherein the inner end of the first section is configured to be pivotably mounted to the crane housing base around a counter jib pivot axis, and wherein the first and second counter jib sections are configured to be connected to each other at their outer end and inner end respectively, and wherein the outer end of the second counter jib section is configured to receive a counter ballast, wherein the method comprises the following steps:

[0045] - placing the crane base on the support at the hoisting site;

[0046] - placing the vertical housing column on the crane base, such that the vertical housing column is horizontally oriented, wherein the inner end of the first counter jib section is connected to the lower end of the vertical housing column,

[0047] - pivotally connecting the second lifting jib section to the first lifting jib section, such that the first and second lifting jib sections are in the folded position, wherein the inner end of the first jib section is connected to the base of the upper crane housing, wherein the first and second lifting jib sections are in a horizontal orientation;

[0048] - pivoting the second lifting jib section relative to the first lifting jib section to the extended position and securing the first and second lifting jib sections relative to each other;

[0049] - placing the crane housing and lifting jib horizontally on top of the vertical housing column and first counter jib section;

[0050] - connecting the base and vertical housing column to each other;

[0051] - connecting the lower crane housing to the lifting tool of the crane tower lifting unit;

[0052] - pivoting the crane tower lifting unit from a horizontal orientation to a vertical orientation, such that the jib unit is also moved to a vertical orientation, wherein the lifting jib and counter jib are in the substantially vertical position;

[0053] - lifting the jib unit with the lifting tool of the crane tower lifting unit, such that a first upper tower segment can be connected to the base end of the slewing jib unit;

[0054] - pivoting the first counter jib section from the vertical position to the horizontal position; - connecting the second counter jib section to the first counter jib section; wherein the method further comprises a crane tower assembly phase, in which- with the crane tower lifting unit in vertical orientation - the crane tower is erected by stacking one or more tower segments one-by-one from below under the slewable lifting jib unit to form the crane tower, in which crane tower assembly phase the crane tower lifting unit lifts the already assembled part of the crane tower.

[0055] This construction method allows most of the tower crane assembly performed by a crew to be performed closer to the ground.

[0056] The invention further relates to the transportation of the tower crane, wherein the crane base, tower segments, crane tower lifting unit, slewable jib unit are transported by transport truck.

[0057] The invention further relates to a method for the assembly of a wind turbine and / or for installing or de-installing of a wind turbine component, e.g. a rotor blade, a nacelle component, wherein use is made of a tower crane described herein.

[0058] The invention also relates to a self-climbing tower crane which is configured to be arranged on a support at a hoisting site, e.g. at a foot of a wind turbine mast, wherein the tower crane comprises:

[0059] - a crane base configured to be placed on the support at the hoisting site,

[0060] - tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base,

[0061] - a crane tower lifting unit which is configured to be mounted on the crane base, and wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below,

[0062] - a slewable jib unit, wherein the slewable jib unit comprises:

[0063] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0064] • a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;

[0065] • a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and wherein the counter jib, e.g. at the outer end, is provided with a counter ballast or a counter cable is provided which is connected to a counter winch to mechanically load the counter jib, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit.

[0066] In an embodiment, the first and second luffing assemblies are independently operable from each other.

[0067] In an embodiment, the crane tower comprises an upper section which is composed of multiple upper tower segments and a lower section which is composed of multiple lower tower segments, the lower section being configured to support the upper section thereon.

[0068] In an embodiment, both the upper and lower tower segments are embodied as tubular girder type tower segments. In another embodiment, the upper tower segments are embodied as tubular girder type tower segments, and the lower tower segments are embodied as lattice structure tower segments. In yet another embodiment, all tower segments are lattice structure tower segments.

[0069] In an embodiment, the upper and lower end portions of the upper and lower tower segments are provided with connectors to rigidly interconnect the tower segments, preferably directly without intermediate connector member.

[0070] In a preferred embodiment, each upper tower segment is embodied as a rectangular tubular girder type tower segment having a height and having outer peripheral walls, preferably made of steel plate. The upper section of the crane tower forming a lengthy and sturdy vertical oriented box structure which distributes the crane loads over the stabiliser devices. These loads for example include torsional loads acting about a vertical axis on the crane tower. In an embodiment, also each lower tower segment is embodied as a rectangular tubular girder type tower segment having a height and having outer peripheral walls, preferably made of steel plate. In a less preferred embodiment than the rectangular / square cross section, the cross section of the upper tower segments and / or lower tower segments is / are of a different shape, e.g. circular or oval.

[0071] In embodiments, the upper and lower portions of the upper tower segments are provided with connectors to rigidly interconnect the upper tower segments.

[0072] Each lower tower segment may be embodied as a circular cross-section tubular girder type tower segment, which has a height, upper and lower end portions, and an outer peripheral wall.

[0073] In practical embodiments, the tower crane can have a height of at least 100 meters, e.g. at least 150 meter, e.g. between 200 - 250 meters.

[0074] In an embodiment, the cross sectional area of the rectangular tubular girder type upper and / or lower tower segments is similar to the cross sectional area of an ISO container, such that regular trucks configured to transport these ISO containers can be used to transport the tower segments.

[0075] In embodiments, e.g. for use with a land-based embodiment of the inventive tower crane, each upper and / or lower tower segment has a height of at least 6 meters, e.g. between 8 and 12 meters, e.g. 10.8 meters. For example, it is envisaged that each upper and / or lower tower segment is to be transported to the hoisting site on a 40 ft. ISO flatbed container, e.g. the container having end members between which the upper segment is horizontally secured for transport, e.g. on a road vehicle. In embodiments, the height of the upper section is at least 10%, preferably at least 20%, and at most 50% of the height of the tower crane when in use at a hoisting site.

[0076] In embodiments, e.g. for use with an offshore application of the inventive tower crane, each upper and / or lower tower segment has a height of at least 12 meters, e.g. between 20 and 30 meters. This, for example, reduces the number of storage positions for tower segments on the crane base when present.

[0077] In embodiments, when in use at a hoisting site adjacent a wind turbine mast, the upper section extends upward beyond the top end of the wind turbine mast, e.g. upward beyond a nacelle placed on top of the wind turbine mast. In embodiments, e.g. in the field of wind turbine installation, e.g. when installing a wind turbine blade, the height of the upper section is at least 25 meters, e.g. between 40 and 60 meters.

[0078] In embodiments, the upper section is composed of between three and six upper segments, e.g. each having a height between 8 and 12 meters, e.g., for onshore application. For an offshore application, in embodiments, the upper section of the crane tower could be composed of two or three upper segments, e.g. each having a height of at least 12 meters.

[0079] In an embodiment, the one or more outer peripheral walls of the upper and / or lower segments are internally reinforced by longitudinal stiffeners extending along the height of the tower segments, e.g. forming reinforced columns along the inside of the outer peripheral walls increasing the longitudinal stiffness of these walls.

[0080] In an embodiment, each lower tower segment comprises an inner lower tower segment and an outer lower tower segment. The inner lower tower segment having a longitudinal axis. The outer lower tower segment has a slightly larger diameter than the inner lower tower segments, such that the outer lower tower segment can telescopically envelope the inner lower tower segment. The outer lower tower segment are movable along the longitudinal axis of the inner lower tower segment between a retracted and an extended position. This allows the lower tower segments to be more easily transported, and the arrangement where the outer lower tower segment envelops the inner tower segments allows the use of a crane tower lifting unit which can only lift objects to a height substantially equal to halve of the lower tower segment in the extended position.

[0081] In an embodiment, the top end of the inner lower tower segment and the base end of the outer lower tower segment are provided with cooperating locking members. The cooperating locking members are configured to secure the inner lower tower segment and outer lower tower segment relative to each other when the outer lower tower segment is in the extended position.

[0082] In an embodiment, the crane housing comprises a lower and an upper crane housing section. The lower crane housing section is configured to be mounted on top of the crane tower. A slew bearing is provided between the lower and upper crane housing section. The slew bearing allows the upper crane housing section to slew relative to the lower crane housing section and the crane tower. The lifting jib and counter jib are connected to the upper crane housing section such that the lifting jib and counter jib can also be slewed relative to the crane tower. A slew drive is provided in practical embodiments. In an embodiment, the upper crane housing section has a base and a vertical housing column. The vertical housing column has a base end and a top end, wherein at the top end the vertical housing column is provided with a luffing sheave assembly, and wherein the base and the vertical housing column are configured to be connected to each other.

[0083] In an embodiment, the first and second luffing assemblies each comprise a luffing sheave assembly which is arranged at or near the top end of the crane housing, preferably at the top end of the vertical housing column, and a luffing winch and associated luffing cable. The luffing cable of the first luffing assembly is guided via the respective luffing sheave assembly the lifting jib, e.g. to the outer end thereof, to enable pivoting of the lifting jib about the lifting jib pivot axis. The luffing cable of the second luffing assembly is guided via the respective luffing sheave assembly to the counter jib, to enable pivoting of the counter jib about the counter jib pivot axis. Preferably, the first and second luffing assemblies are independently operable from each other.

[0084] In an embodiment, the luffing winches of the first and second luffing assemblies are arranged on the upper crane housing section, e.g. inside the upper crane housing section.

[0085] In practical embodiments, the tower crane has a hoisting winch and an associated hoisting cable which depends from a hoisting sheave assembly on the lifting jib, e.g. the housing sheave assembly being mounted at the outer end of the lifting jib. In another embodiment, the hoisting sheave assembly is mounted on a jib trolley that travels over the lifting jib to allow multiple positions of the hoisting sheave assembly. A load connector is suspended from the hoisting cable, e.g. a blade lifting tool being suspended from the load connector when handling a blade of a wind turbine with the tower crane.

[0086] In an embodiment, the hoisting cable extends between the hoisting sheave assembly and the load connector in a multi-fall arrangement.

[0087] In an embodiment, the hoisting winch is arranged on the jib unit.

[0088] In a preferred embodiment, the hoisting winch is arranged at the lower end of the tower crane, e.g. on the crane base. In an embodiment, the hoisting cable extends from the hoisting winch at the lower end of the tower crane, e.g. on the crane base, along a side of the crane tower to or into the crane housing and the hoisting cable then extends from the crane housing to a hoisting sheave assembly, e.g. arranged at the outer end of the lifting jib, and the hoisting cable extends between the hoisting sheave assembly and a load connector. Considering the height of tower crane, e.g. 150 - 200 meters, a very long hoisting cable is required, especially when a multi-fall arrangement is used, this results in a very heavy hoisting winch, e.g. in view of the length of the hoisting cable to be stored, e.g. on a drum of the winch. By having the hoisting winch arranged at the crane base of the tower crane instead of in the crane housing or elsewhere on the jib unit the slewable jib unit becomes much lighter and easier to lift, which enhances the installation process and the stability of the tower crane, e.g. reducing loads on the one or more stabiliser devices when present.

[0089] In an embodiment, the crane tower is provided with one or more upper stabiliser devices and one or more lower stabiliser devices, each configured to horizontally connect the crane tower to an external tall structure, e.g. a wind turbine mast. The one or more upper stabiliser devices are configured to connect to an upper portion of the crane tower, and the one or more lower stabiliser devices being configured to connect to a lower portion of the crane tower.

[0090] In an embodiment, the one or more upper and lower stabiliser devices are configured to clamp onto, e.g. frictionally engage, a wind turbine mast.

[0091] In an embodiment, the one or more upper stabiliser devices are configured to travel up and down along the upper section of the crane tower. Preferably, the one or more lower stabiliser devices are configured to travel up and down along the lower section of the crane tower.

[0092] In an embodiment, tower segments, at least at the upper portion of the crane tower, are each provided with at least one guide rail extending along the height of the upper tower segment such that the guide rails of the interconnected upper tower segments form a substantially continuous guide rail. The one or more stabiliser devices are configured to move along the continuous guide rail up and down the crane tower.

[0093] In an embodiment, the crane is provided with one or more stabiliser hoist devices, e.g. a winch, arranged on the crane tower and which is configured to hoist one or more stabiliser devices along the crane tower.

[0094] In an embodiment, the crane tower lifting unit comprises a vertical lifting column, and optionally a base, e.g. formed by or combined with the crane base. The vertical lifting column comprises a base end and a top end, wherein the vertical lifting column is pivotable between a horizontal position and a vertical position relative to the base, e.g. the crane base. The crane tower lifting unit further comprises a lifting tool which is configured to engage a tower segment, possibly the entire already assembled crane tower, e.g. at a lower end thereof. The lifting unit further comprises a hoisting assembly for the lifting tool. The hoisting assembly, in embodiments, comprises one or more hoisting winches and associated hoisting cables and a hoisting sheave assembly arranged at or near the top end of the vertical lifting column. The hoisting cable is guided via the hoisting sheave assembly to the lifting tool.

[0095] In an embodiment, the vertical lifting column of the crane tower lifting unit is provided with a track which extends between the base end and the top end of the vertical lifting column, wherein the lifting tool is movable up and down along the track.

[0096] In an embodiment, the crane base is provided with a tower segment transfer trolley, which is horizontally movable, e.g. along a corresponding track, between the one or more storage positions for one or more tower segments on the crane base and an installation position at the lifting unit. For example, the transfer trolley is provided with drive unit configured to move the transfer trolley along the track. The transfer trolley is provided with one or more mounting members allowing to retain a tower segment, e.g. on which a tower segment can be mounted, e.g. by an auxiliary crane. The transfer trolley is configured to move the tower segment from the storage position to the installation position, e.g. where the tower segment is positioned underneath and aligned with the lifted crane tower. This allows for a quick and effective assembly of the tower crane. It will be appreciated that the tower segment transfer trolley can also be employed when the crane tower is to be disassembled.

[0097] The invention further relates to a jack-up vessel provided with a self-climbing tower crane as discussed herein, e.g. the tower crane being arranged on the hull or on a mobile cantilever of the jack-up vessel. For example, the tower crane comprises:

[0098] - a crane base arranged on the jack-up vessel, e.g. on the hull or the cantilever or integrated therewith,

[0099] - tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base,

[0100] - a crane tower lifting unit which is arranged on the deck of the jack-up vessel, and wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below,

[0101] - a slewable jib unit, wherein the slewable jib unit comprises:

[0102] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0103] • a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;

[0104] • optionally, a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another, e.g. from below, to lengthen the crane tower under the slewable jib unit.

[0105] In an embodiment, the tower segments are arranged, preferably in vertical orientation, on the deck or the cantilever, when present, of the vessel in a respective storage position, e.g. the tower segments are stored vertically during transport.

[0106] In an embodiment, a tower segment transfer trolley is arranged on the jack-up vessel, wherein the tower segment transfer trolley is configured to engage and move the tower segments, e.g. in the vertical orientation thereof, from the respective storage position to the installation position, e.g. below and aligned with the lifted crane tower.

[0107] In an embodiment, the tower segments are transported in a horizontal orientation thereof during transportation, e.g. during the travel from a port to the installation site, wherein before installation of the tower segment the tower segment is moved from the horizontal to the vertical orientation, e.g. by an auxiliary crane on the jack-up vessel.

[0108] In an embodiment, the crane base and / or the crane tower lifting unit is / are integrated with the hull or the cantilever, when present, of the jack-up vessel.

[0109] The invention further relates to a method for installing or maintenance of a wind turbine component on a wind turbine mast, wherein use is made of a self-climbing crane as described herein wherein the self-climbing crane is arranged on a jack-up vessel, e.g. wherein the crane tower is arranged at a distance, e.g. more than 10 meters, from the wind turbine mast.

[0110] The jack-up vessel provides a stable base for the self-climbing tower crane allowing for a stable operation of the crane. Furthermore, by arranging the self-climbing crane on a jack-up vessel, the tower crane can be erected at some distance from the wind turbine mast instead of being erected close to and along the wind turbine mast. This may be especially beneficial when performing activities related to very large offshore wind turbines, e.g. wind turbine with a wind turbine mast length of over 150 meters, e.g. over 200 meters. The wind turbine blades of such wind turbines are very long and heavy and have to be lifted at their centre of gravity. If the tower crane would be erected closely along the wind turbine mast, a rather lengthy and robust (and therefore heavy) lifting jib would be required. By providing the self-climbing crane on a jack-up vessel and erecting the tower crane at some distance from the wind turbine mast, a shorter lifting jib can be used, as the tower crane can be positioned closer to the centre of gravity of the wind turbine blade to be installed. Additionally, the jack-up vessel can also be positioned such that the tower crane is close to the wind turbine mast, which is beneficial for example when installing the nacelle on the wind turbine mast.

[0111] In an embodiment, the jack-up vessel sails to the installation site, e.g. a wind park, wherein the tower crane is not yet erected, e.g. the tower segments are stored on the deck of the vessel, wherein once the jack-up vessel is correctly positioned and the legs extended, the tower crane is erected on the deck of the vessel, and used to install a wind turbine component. This allows the jack-up vessel to be provided with a very tall crane without the negative consequences of such a tall crane during transport.

[0112] In an embodiment, an auxiliary vessel, e.g. a feeder vessel, transports wind turbine components from land, e.g. a port, to the jack-up vessel positioned at the installation site. In an embodiment, the tower crane picks up the component from the feeder vessel and then lifts the component to the installation height. In another approach, the self-climbing crane or an auxiliary crane is used to move the wind turbine component from the deck of the auxiliary vessel to the deck of the jack-up vessel.

[0113] The invention also relates to a self-climbing tower crane which is configured to be mounted on and extend along an offshore wind turbine, wherein the turbine comprises a wind turbine mast, wherein the tower crane comprises:

[0114] - a crane base, e.g. an annular crane base, configured to be mounted on or near the lower end of a wind turbine mast, e.g. on support brackets provided on a lower end of a wind turbine mast or on a foundation, e.g. an offshore foundation, e.g. a monopile, thereon,

[0115] - tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the annular crane base ,

[0116] - a crane tower lifting unit which is mounted on the annular crane base, and wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below, - a slewable jib unit, wherein the slewable jib unit comprises:

[0117] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0118] • a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;

[0119] • a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; and wherein a counter cable is provided, and wherein an associated counter winch is arranged on the crane base, wherein the counter cable is reeved so as to exert a mechanical load on the counter jib, and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit.

[0120] The counter jib is, e.g. at the outer end thereof, mechanically loaded, so a force being exerted, by the counter cable. The counter cable extends between the counter jib and an associated counter winch which is arranged on or in the proximity of the crane base. By operating the counter winch, the force that is applied on the counter jib due to the counter cable applying a force can be varied. The counter cable in combination with the counter winch can therefore act as a variable counter ballast. The use of a counter cable instead of a counter ballast also reduces the weight of the slewable jib unit, which enhances the assembly process of the inventive crane. Also stability is increased as less weight is present at the top of the crane.

[0121] In an embodiment, wherein the first and second luffing assemblies are independently operable from each other.

[0122] In an embodiment, the first and second luffing assemblies are embodied with a respective first and second luffing cylinder, e.g. hydraulic luffing cylinders. The first luffing cylinder is at one end connected to the top end of the crane housing and the other end of the first luffing cylinder is connected to the lifting jib. The second luffing cylinder is at one end connected to the top end of the crane housing and the other end of the second luffing cylinder is connected to the counter jib. The first and second lifting cylinders are configured to pivot the respective one of the lifting jib and the counter jib between the substantially horizontal orientation and the substantially upward vertical orientation.

[0123] In practical embodiments the luffing cylinders are configured and operated to control the luffing angle of the respective jib, so that the jib is not able to pivot without operation of the luffing cylinder.

[0124] In practical embodiments, the luffing cylinders are provided in pairs.

[0125] In an embodiment, the crane base is configured to be mounted on a lower portion of the wind turbine mast, e.g. the lower portion of the wind turbine mast is provided with supporting brackets onto which the crane base can be mounted, or on a foundation, e.g. on a monopile, a tripod, or other fixed offshore foundation or on a floating foundation for an offshore wind turbine.

[0126] In an embodiment, the crane base is an annular crane base configured to be mounted on the lower part of a wind turbine mast or on a foundation, e.g. on supporting brackets, e.g. diametrically opposed trunnions, wherein the crane base encircles the lower part of the wind turbine mast or (part of) the foundation.

[0127] The annular crane base distributes the loads of the tower crane effectively and creates a stable base for the crane tower. Furthermore, the annular crane base may provide a large area to store tower crane components, e.g. tower segments at storage positions. For example, an annular crane base, e.g. to be composed of two crane base segments, allows the crane base to be mounted onto the wind turbine or foundation with all components of the tower crane already mounted on the crane base. The tower crane thus can independently erect itself once the annular crane base has been mounted on the wind turbine or foundation, e.g. of an offshore wind turbine

[0128] The annular crane base may have a circular inner contour and a circular outer contour, but other contour shapes of the inner and / or outer contour may also be provided, e.g. polygonal, oval, or even a square or rectangular contour.

[0129] In embodiments, the annular crane base is composed of two crane base segments which are joined to one another in the process of mounting the tower crane on the support so that the completed crane base encircles the lower end of the mast of the wind turbine or the foundation, e.g. a mast mounting structure of the foundation, e.g. a floating offshore foundation.

[0130] The crane base, e.g. base segments thereof, can have locking devices configured to secure the crane base onto the support, e.g. on brackets mounted at the lower end of the wind turbine mast or on a mast mounting structure of the foundation.

[0131] In an embodiment, the base segments are hinged to one another, allowing to place the crane base in open state on the support and to then bring the base segments in a closed state wherein the base segments encircle the lower end of the mast of the wind turbine or a mast mounting structure of the foundation, e.g. a floating offshore foundation.

[0132] In an embodiment, the tower crane is transported, e.g. on a crane vessel, to the offshore wind turbine. The wind turbine is, preferably, already installed at its operational site or in close proximity thereof. For example, a floating foundation is already moored at its operational site at sea.

[0133] In an embodiment, one or more cranes of a vessel, e.g. of the same vessel used for transportation of the tower crane, is used for the temporary installation of the crane tower on the offshore wind turbine.

[0134] In an embodiment, the tower segments are arranged in their vertical orientation and side by side on the crane base, e.g. in an array extending over an arc-segment of the annular crane base. In an embodiment, the crane base comprises a magazine in which the tower segments are stored, and which magazine is configured and operated to move the tower segments in succession from their respective storage position to the position where the tower segment is assembled with the crane tower. Preferably, the tower segments are stored vertically in the magazine.

[0135] In a preferred embodiment, the tower segment transfer trolley is arranged on the annular crane base and is configured to engage and move the tower segment in its vertical orientation from its storage position, e.g. in the magazine, to the installation position, e.g. below and aligned with the lifted crane tower.

[0136] In an embodiment, the annular crane base is provided with a transfer trolley track, which transfer trolley track extends along a part of or the entire annular crane base. The tower segment transfer trolley is configured to engage and move along the transfer trolley track. The transfer trolley being able to move along the trolley track between the storage position(s) of the tower segment to the installation position at the crane tower lifting unit.

[0137] In an embodiment, the annular crane base comprises two base segments, wherein the two base segments are configured to be connected to each other. Preferably, a first base segment is configured to mounted on one or more, e.g. two, support brackets provided on the lower part of the wind turbine mast or the foundation, e.g. the monopile. Subsequently the second base segment is mounted. This could be on one or more additional support brackets, wherein the base segments may be connected to one another. In embodiments, the second base segment is to be connected to the first base segment and not supported on such additional support brackets.

[0138] In an embodiment, the base segments of the crane base comprise cooperating connection members, e.g. two cooperating hooks, which are configured to engage each other and connect the two base segments to one another. Each base segment may be provided with two connection members, e.g. at each end thereof. Preferably, the connection member of the first base segment is embodied as a hook, wherein the hook opening faces upward, and the connection member of the second base segment is embodied as a hook, wherein the hook opening faces downward, such that when the first base segment is first mounted on the wind turbine mast or foundation, the second base segment can be lowered and the hooks engage each other to form a connection.

[0139] In an alternative embodiment, the first and second base segments are connected to each other with a pin-hole connection, e.g. using actuator driven pins.

[0140] In an embodiment, each semi-circular base segment is provided with a segment transfer trolley track, wherein - when the two semi-circular base segments are connected to each other - the segment transfer trolley tracks form a substantially continuous transfer trolley track along which the tower segment transfer trolley can move, e.g. the transfer trolley can move from one semi-circular base segment to the other.

[0141] In an embodiment, the hoisting cable extends from the hoisting winch to a counter jib sheave assembly provided at the outer end of the counter jib. The hoisting cable extends from the counter jib sheave assembly to a crane housing sheave assembly provided at the top end of the crane housing; from the crane housing sheave assembly the hoisting cable extends to a lifting jib sheave assembly provided at the outer end of the lifting jib. The hoisting cable extends from the lifting jib sheave assembly to the lifting tool. In an embodiment, the counter cable extends from the counter winch to the counter jib sheave assembly provided at the outer end of the counter jib.

[0142] In an embodiment, the tower crane is provided with a winch trolley, wherein the hoisting winch and the counter cable winch are mounted on the winch trolley. The winch trolley is configured to move along a semi-circular or circular path relative to the crane base, e.g. the annular crane base. The winch trolley allows the hoisting winch and counter cable winch to follow, e.g. move along with, the counter jib when the slewable jib unit is slewing, this ensures that the hoisting cable and counter cable can move vertical and lateral from the winches to sheave assemblies at the end of the counter jib without any substantial angular movement of the cables.

[0143] In an embodiment, the crane base is provided with a winch trolley track, wherein the winch trolley track extends along a part of or, preferably along, the entire annular crane base. The winch trolley is configured to engage and move along the winch trolley track.

[0144] In an embodiment, each semi-circular segment is provided with a winch trolley track, wherein - when the two semi-circular segments are connected to each other - the winch trolley tracks form a substantially continuous winch trolley track along which the winch transfer trolley can move along, e.g. the winch trolley can move from one semi-circular segment to the other.

[0145] In an embodiment, the transfer trolley track and the winch trolley track form a single circular track that extends along the entire crane base along which both the transfer and winch trolley can move.

[0146] In an embodiment, the support brackets arranged on the lower end of the mast or on the foundation, e.g. the monopile, are embodied as trunnions, wherein two trunnions are arranged at diametrically opposed positions. It is known to provide trunnions for lifting the mast or foundation, e.g. monopile, wherein hoisting cables are attached to the trunnions. In embodiments, the invention envisages that trunnions are used as support for the crane base of the tower crane, e.g. for dual use during lifting of the mast / foundation and as support for the crane base of the tower crane.

[0147] In an embodiment, the trunnions are configured to be engaged during the upending and / or lifting of the wind turbine mast or monopile. For example, one or more hoisting cables are attached to the trunnions which are used to support an upending and / or lifting operation of the wind turbine mast or monopile. The trunnions are configured to support the entire weight of the wind turbine mast or monopile.

[0148] In an embodiment, the two trunnions are interconnected by a trunnion beam extending transverse through the mast or the foundation, e.g. the monopile. For example, the trunnions are in part formed as the two outer ends of cylindrical trunnion beam which extends between two diametrically opposed points on the circumference of the wind turbine or the foundation, e.g. monopile, and the outer ends of the trunnions beam extends outward to form the trunnions which are configured to support the crane base.

[0149] It is noted that trunnions on the monopile and the lower end of a wind turbine mast are known for hoisting the monopile or wind turbine mast by means of a crane. In the known configuration, the trunnions are only connected to the wall of the monopile or wind turbine mast. By interconnecting the trunnions by means of the trunnion beam a sturdy support for the tower crane is provided. The beam can be provided when manufacturing the monopile or mast. In an embodiment, the trunnion beam is installed at a later stage, e.g. after installation of the foundation, e.g. monopile, in the seabed. For example, the trunnion beam is bolted or welded in-situ in the already installed monopile.

[0150] In an embodiment, a base segment, e.g. the first base segment, of the crane base comprises a support structure which is configured to engage the support bracket(s), preferably two trunnions. The support structure comprises two support members which are each configured to engage one of the support brackets, e.g. trunnions. For example, the support members each comprise a receiving space which is configured to receive the support bracket, e.g. trunnion, such that the first base segment is supported by the support brackets. Preferably, the support members further comprises a guiding structure, e.g. a funnel, which help guide the support members such that the support brackets are received in the receiving space, making the installation of the base segment easier.

[0151] In an embodiment, the first base segment comprises an anti-tilt support mechanism which is configured to support the first base segment when the first base segment is mounted on the support brackets, e.g. two trunnions. The support mechanism is configured to engage the wind turbine mast or foundation at a location below support brackets, e.g. two trunnions, and to prevent tilting of the first base segment. When the first base segment is first mounted to two support brackets at ends of the base segment, the first base segments will be supported only at the two outer ends of the semi-circular base segment. If no other counteracting force is applied, the first base segment would tilt relative to the wind turbine mast or foundation, e.g. monopile.

[0152] In an embodiment, the anti-tilt support mechanism comprises an engagement pad which is configured to engage the wind turbine mast or foundation, e.g. the monopile. The engagement pad is arranged on a mobile engagement frame, e.g. at a lower end of an engagement frame. For example, the engagement frame is pivotably connected to the first base segment at a frame connection point and extends downward from the first base segment. Preferably, the engagement pad is pivotably connected to the engagement frame.

[0153] In an embodiment, the anti-tilt support mechanism further comprises an actuating assembly which is configured to operate the mobile frame and thereby move the engagement pad, e.g. to bring the engagement pad into engagement with the wind turbine mast or the foundation, e.g. the monopile.

[0154] In an embodiment, the actuating assembly comprises a first rod which is at one end pivotably connected to a lower side of the first base segment, and a second rod which is pivotably connected to a lower end of the first rod at a rod connection point. The second rod is at the other end pivotably connected to the lower end of the engagement frame. The actuating mechanism further comprises one or more actuating cylinders, e.g. one or more hydraulic cylinders, which extend from the lower end of the first base segment to the rod connection point. By retracting the one or more actuating cylinders the engagement frame is rotated around the connection point. Preferably, - when the one or more actuating cylinders are extended - the first and second rods define a first angle smaller than 180 degrees, and wherein - once the one or more actuating cylinders are retracted - the first angle is larger than 180 degrees. By having a first angle which is larger than 180 degrees it ensures that, without extending the one or more actuating cylinders, the engagement pad remains engaged with the wind turbine mast.

[0155] In an alternative embodiment, the actuating assembly comprises one or more actuating cylinders, e.g. one or more hydraulic cylinders, which extend between the first base segment and the engagement frame, e.g. wherein the one or more actuating cylinders are pivotably connected to the engagement frame. The one or more hydraulic cylinders are configured to operate the frame, e.g. to rotate the engagement frame around the frame connection point in order to bring the engagement pad into engagement with the wind turbine mast or foundation. In an alternative embodiment to the presence of a dedicated counter cable, the hoisting cable extends from the hoisting winch to a counter jib sheave assembly provided at the outer end of the counter jib. The hoisting cable extends from the counter jib sheave assembly to a crane housing sheave assembly provided at the top end of the crane housing; from the crane housing sheave assembly the hoisting cable extends to a lifting jib sheave assembly provided at the outer end of the lifting jib. The hoisting cable extends from the lifting jib sheave assembly to the lifting tool, from where the hoisting cable extends back towards the lifting jib sheave assembly, and from the lifting jib sheave assembly to the crane housing sheave assembly. The hoisting cable then extends towards the counter jib sheave assembly, from where it extends towards the hoisting winch. In this alternative embodiment, the hoisting cable acts as the counter cable, such that no separate counter cable and counter cable winch is needed. Due to the considerable height the hoisting winch would require a significant cable storage capacity on the drum. Additionally, due to the arrangement of the hoisting cable, the lifting jib and the counter jib are always symmetrical. While the embodiment with a separate counter cable and counter winch allows for non-symmetrical configurations, allowing for the use of different lengths of the lifting jib and counter jib.

[0156] In an embodiment, before the annular crane base is mounted on the wind turbine mast or foundation, the crane tower lifting unit is mounted on one of the base segments, e.g. the first base segment, and the tower segments are already stored on one of the base segments, e.g. on the second base segment, and the winch trolley and tower segment transfer trolley are already engaged with the tracks provided on the base, and the slewable jib unit is already at the installation position at the crane tower lifting unit, e.g. on the first base segment. All components of the crane tower are thus already provided on the crane base, e.g. on the two base segments thereof, once the crane base has been mounted on the wind turbine mast, the crane tower can assemble itself without the need of additional support, e.g. from a vessel.

[0157] In an embodiment, the tower segment are all stored on one of the base segments, e.g. on the second base segment, e.g. the magazine is provided on one of the base segments, and the crane lifting unit is provided on the other base segment, e.g. on the first base segment.

[0158] In an embodiment, each tower segment is provided with blade manipulator trolley track, preferably on the opposite side relative to the guide rail(s) for the horizontal stabiliser(s), which extend along the length of the tower segment, such that a substantially continuous blade manipulator trolley track is formed along the length of the crane tower. Preferably, the rails of the blade manipulator trolley track are integrated with the chords of the tower segments. In an embodiment, the wind turbine blade is suspended from the hoist cable by a spreader structure that extends along the length of the blade, e.g. above the blade, from an inner end thereof that is at or near the root of the blade to an outer end that is beyond the centre of gravity of the blade. Herein the hoisting cable, preferably, engages on the spreader structure in vertical alignment with the centre of gravity of the blade so that the blade is effectively engaged at the COG thereof by the spreader structure.

[0159] In an embodiment, the tower crane further comprises a blade manipulator assembly comprising: a blade manipulator trolley engaging the blade manipulator trolley track and being movable along the track in vertical direction, a blade manipulator trolley drive for moving the blade manipulator trolley along the track, a blade manipulator which is configured to engage the blade lifting tool, wherein the blade manipulator is supported by the blade manipulator trolley and configured to provide controlled motion in one or more degrees of freedom of the blade lifting tool and the blade engaged thereby.

[0160] The blade manipulator assembly can be provided for both land-based and offshore based versions of the self-climbing tower.

[0161] Preferably, the lifting jib has a length such that the hoisting cable can engage on a horizontally oriented blade at the centre of gravity (COG) thereof, whilst the manipulator assembly engages the blade lifting tool. In practical embodiments, the COG of the blade can be more than 25 meters away from the root end, e.g. between 30 and 40 meters away from the root end. It will be appreciated that this induces significant loads on the crane mast that is to be structured accordingly.

[0162] Preferably, the blade manipulator trolley is driven, at least during the lifting of the blade, by an associated trolley drive, e.g. a cable and winch drive or a rack and pinion drive. In another embodiment, the blade manipulator trolley passively follows the lifting motion of the blade that is caused by operation of the hoist system.

[0163] In a preferred embodiment, the crane tower and the blade manipulator trolley track extend above or level to the horizontal axis rotational hub of the nacelle, allowing the trolley, the blade manipulator engaged with the spreader structure, and the wind turbine root to be level with the rotational hub of the nacelle, allowing the blade to be horizontally installed on the nacelle.

[0164] Preferably, the blade is kept in horizontal orientation while being lifted, so that both the lower receiving position thereof and the blade installation position are horizontal. Other approaches, e.g. wherein the blade is tilted to an inclined blade installation position are also envisaged. In embodiments, the blade is attached to the hub in an inclined orientation, e.g. including an angle of 5 - 40° with the vertical, e.g. between 10 - 25°. This inclined orientation is deemed less attractive in view of controlled lifting and attachment of the blade, in particular in view of the large dimensions of the blade.

[0165] In an embodiment, a physical link, e.g. releasable, is established between the blade lifting tool of the hoist system and the trolley. This, for example, allows for an operation wherein the manipulator trolley is effectively driven as the tool which holds the blade is lifted by the hoist system. This link may also be of use when the blade lifting tool is to be lowered without a blade being held, wherein the link has the effect that undue sway motion of the blade lifting tool is prevented.

[0166] In particular when performed blade installation in the context of a floating foundation, the inventive approach and crane has the advantage that the blade is under control by the cooperation of the blade manipulator assembly which travels up along the crane mast during lifting and the hoist system. All these components of the temporarily installed tower crane are subject to the same motion(s) as the floating foundation and the wind turbine mast and nacelle thereon. This enhances the lifting and attachment steps for the blade compared to prior art approaches.

[0167] In an embodiment, the blade manipulator comprises:

[0168] - a lateral guide bracket, which is connected to the blade manipulator trolley,

[0169] - an axial guide bracket which is mounted on and movable in the lateral direction of the blade along the lateral guide bracket,

[0170] - an engagement member configured to be engaged with the blade lifting tool wherein the engagement member is mounted on and movable in the axial direction of the blade along the axial guide member.

[0171] The lateral and axial guide members in combination with the trolley on which the blade manipulator is supported allow the engagement member to be moved in the axial and lateral directions of the blade and in the vertical direction. This allows for a precise positioning of the blade root end with respect to the rotational hub of the nacelle. Preferably, the connection between the axial guide bracket and the engagement member allows for a yaw movement of the blade root end, and optionally a roll movement of the blade root end.

[0172] In embodiments, the blade manipulator assembly comprises an actuating assembly and an associated positioning system configured and operated to position the root end of the blade when attaching the blade to the hub, e.g. the actuating assembly comprising a lateral and axial drive to move the axial guide in the lateral direction and to move the engagement member in the lateral direction respectively. Preferably, the actuating assembly comprising position actuators to move the engagement member in yaw direction, and optionally in pitch direction.

[0173] For example, the positioning system comprises one or more sensors to detect the actual position and / or motion of the blade relative to the mounting structure of the hub, e.g. during the phase of mating the blade root with the mounting structure.

[0174] For example, the actuating assembly is configured to dampen motion(s) of the blade, e.g. to dampen any sway motion(s) in a horizontal plane.

[0175] In an embodiment, the blade manipulator assembly further comprises one or more, preferably three, manipulator winches and associated manipulator cables, wherein the manipulator winches are arranged on the blade manipulator, preferably on the engagement member, preferably in an inverted pyramid configuration. The manipulator cables extend between the manipulator winches and the blade lifting tool. The manipulator winches and cables allow the blade lifting tool and the blade to be pulled towards the blade manipulator, e.g. the blade being loaded into the blade lifting tool away from the crane tower and manipulator and being pulled closer to the blade manipulator by spooling in winch, until the blade manipulator and the blade lifting tool are in engagement with each other. Preferably, the manipulator winches keep the associated cables taught when the blade manipulator and the spreader structure are in engagement with each other.

[0176] In an embodiment, the blade manipulator assembly is already engaged to the blade manipulator track of a tower segment while the tower segment is in a storage position on the crane base.

[0177] In an embodiment, the height of the crane tower erected on the annular crane base is between 100 - 200 meters high, preferably between 140 - 180 meters. In an embodiment, e.g. for application offshore, the crane tower comprises from five to ten tower segments, preferably six tower segments, wherein each tower segment has a height of between 20 - 30 meters, preferably 25 meters.

[0178] In an embodiment, the stabiliser devices are initially arranged on the crane base, e.g. the annular crane base.

[0179] In an embodiment, the crane tower lifting unit is pre-mounted on the crane base and the slewable jib unit is placed in an installation position at or in proximity of the crane tower lifting unit.

[0180] For example, the tower segments are arranged in their vertical orientation and side by side on the crane base, e.g. in an array extending over an arc-segment of the annular crane base, e.g. the crane base comprises a transfer device, e.g. a segment transfer trolley, which is configured and operated to move the tower segments in succession from their respective storage position to the position where the tower segment is assembled with the crane tower.

[0181] In an embodiment, the method comprises the following steps:

[0182] - transporting the tower crane to the offshore wind turbine, e.g. on a crane vessel;

[0183] - mounting the crane base on the lower end of the wind turbine mast or on the floating foundation, e.g. a monopile, e.g. on support brackets provided on the lower end of the wind turbine mast or on a mast mounting structure of the floating foundation.

[0184] In an embodiment, the lower end of the wind turbine mast or the foundation, e.g. the monopile, is provided with support brackets, e.g. two trunnions, wherein the mounting of the crane base comprises the following steps: mounting the first base segment to the support brackets, preferably wherein the support structure of the first base segment engages each of the support brackets, and wherein, preferably, the anti-tilt support mechanism of the first base segment engages the wind turbine mast or foundation; connecting the second base segment to the first base segment, e.g. via a pin-hole connection.

[0185] In an embodiment, the method comprises a crane tower assembly phase, in which the crane tower is erected by stacking one or more tower segments one-by-one from below under the slewable lifting jib unit to form the crane tower, in which crane tower assembly phase the crane tower lifting unit lifts the already assembled part of the crane tower. In a preferred embodiment of the method, the lifting jib and the counter jib are in the substantially vertical upward orientation during the crane tower assembly phase.

[0186] In an embodiment, the annular crane base comprises two base segments, wherein first a first base segment is mounted and wherein subsequently the second base segment is mounted and connected to the first base segment.

[0187] In an embodiment, during the crane tower assembly phase the tower segments are engaged and moved from a storage position on the crane base to an installation position at the crane tower lifting unit by a tower segment transfer trolley. In the installation position the tower segment is below and aligned with the lifted crane tower.

[0188] In an embodiment, a vessel equipped with one or more cranes are used to transfer the tower crane to the offshore wind turbine.

[0189] The invention further relates to a method for operating a tower crane described herein, wherein the winch trolley described herein travels along the winch trolley track when the slewable jib unit slews, such that the winch trolley remains aligned with the outer end of the counter jib.

[0190] The invention further relates to a method for installing a wind turbine blade on a horizontal axis rotational hub of a wind turbine, e.g. on land or offshore, the wind turbine comprising a wind turbine mast and a nacelle with a horizontal axis rotational hub provided on the top end of the wind turbine mast, wherein use is made of the tower crane described herein, wherein the method comprises lifting a blade to be installed to a blade installation position and attaching the blade that has been lifted to the blade installation position to the horizontal axis rotational hub of the wind turbine, wherein the wind turbine blade is suspended from the hoisting cable by a blade lifting tool, wherein the method comprises:

[0191] - bringing the blade manipulator trolley in a lower position thereof,

[0192] - bringing the blade lifting tool in engagement with the blade manipulator in the lower position thereof,

[0193] - lifting the wind turbine blade to the blade installation position by operating the hoisting winch and simultaneously moving the blade manipulator trolley along the blade manipulator trolley track, e.g. by the trolley drive, such that the blade manipulator and the blade lifting tool stay in constant engagement with each other. The constant engagement of the blade lifting tool with the blade manipulator reduces the swinging of the blade with respect to the tower crane, this allows for easier installation of the wind turbine blade.

[0194] In an embodiment, the blade manipulator and the blade lifting tool are brought in engagement with each other by operating the manipulator winches. Preferably, wherein the manipulator cables are reeled in by operating the manipulator winches, such that the blade lifting tool supporting the blade is pulled towards brought in engagement with the blade manipulator.

[0195] In embodiments, the actuating assembly and associated positioning system are operated to position the root end of the blade when attaching the blade to the rotational hub,

[0196] In an embodiment, a vessel used for transportation of the tower crane is also used for transportation of the blades to be installed on the offshore wind turbine. For example, the vessel is equipped with one or more cranes that are first used to transfer the tower crane to the offshore wind turbine, and then used for transfer of the blade to be installed from the vessel, e.g. from a blade rack mounted thereon, to the lower receiving position

[0197] In an alternative embodiment, it is envisaged that the hoist system, comprising the hoisting cable, hoisting winch, and the blade lifting tool, of the tower crane is used to pick-up the blade directly from a vessel, e.g. dedicated blade supply vessel. Herein the blade is held on the vessel by means of a motion compensated platform, e.g. a heave compensated platform, so that the blade can be held in a motion compensated mode before the hoist system is engaged with the blade for its pick-up, e.g. using the spreader structure. Possibly, the blade is then first lifted a bit to clear the vessel, or platform thereof, and only then brought into engagement with the blade manipulator, e.g. by reeling in the blade manipulator cables. So the blade is then first attached to the hoist system and then to the manipulator assembly. There after the blade is lifted to a blade installation position.

[0198] An aspect of the present invention relates to a self-climbing tower crane which is configured to be arranged on a support, e.g. a support at or near a foot of a wind turbine mast, wherein the tower crane comprises:

[0199] - a crane base configured to be placed on the support,

[0200] - tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base, - a crane tower lifting unit which is configured to be mounted on the crane base, and wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below,

[0201] - a slewable jib unit, wherein the slewable jib unit comprises:

[0202] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0203] • a lifting jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a first luffing assembly

[0204] • a counter jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a second luffing assembly and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit, wherein the crane base is configured to store the tower segments thereon at respective storage positions (SP), preferably in a vertical orientation, and wherein the crane base is provided with a tower segment transfer trolley, wherein the tower segment transfer trolley is configured to engage a tower segment at the respective storage position (SP) and to move the tower segment, preferably in a vertical orientation, to an installation position (IP) at or in proximity of the crane tower lifting unit.

[0205] In an embodiment, the crane base is provided with a transfer trolley track and wherein the tower segment transfer trolley is movable along the track, e.g. wherein the tower segment transfer trolley is provided with drive unit configured to move the segment transfer trolley along the transfer trolley track.

[0206] In an embodiment, the transfer trolley track is circular or semi-circular.

[0207] In an embodiment, the crane base is an annular crane base and comprises two base segments, wherein the two base segments are configured to be connected to each other, e.g. wherein at least one base segments, e.g. both base segments, is / are provided with a transfer trolley track. In an embodiment, the tower segment transfer trolley is provided with mounting member, e.g. configured to cooperate with connectors of a tower segment, wherein a tower segment is to be connected to the mounting members of the tower segment transfer trolley.

[0208] An aspect of the invention relates to a self-climbing tower crane which is configured to be arranged on a support, e.g. a support at or near a foot of a wind turbine mast, wherein the tower crane comprises:

[0209] - a crane base configured to be placed on the support,

[0210] - tower segments which are configured to be stacked onto one another, e.g. from below, in order to erect a crane tower which is composed of the tower segments on the crane base,

[0211] - a slewable jib unit, wherein the slewable jib unit comprises:

[0212] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0213] • a lifting jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a first luffing assembly,

[0214] • optionally, a counter jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a second luffing assembly, and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another, e.g. from below, to lengthen the crane tower under the slewable jib unit, wherein the tower crane has a hoisting winch and an associated hoisting cable which depends from a hoisting sheave assembly on the lifting jib, and wherein the tower crane is provided with a winch trolley on which at least the hoisting winch for the hoisting cable is mounted is mounted, wherein the winch trolley is configured to move along a semi-circular or circular track provided on the crane base, e.g. the annular crane base.

[0215] In this aspect, the crane tower can be assembled from below, but in an alternative the crane tower is assembled by stacking a further segment on top of the already assembled part of the crane tower, just below the jib unit, as is known for tower cranes.

[0216] In an embodiment, the counter jib is present in the slewable jib unit.

[0217] In an embodiment, a counter ballast is mounted on the counter jib, e.g. at the outer end of the counter jib. In another embodiment, a counter ballast action is created as the tower crane is provided with a counter cable and an associated counter winch, wherein the counter cable is reeved so as to exert a mechanical load on the counter jib. In the latter embodiment, preferably, also the counter winch is mounted on the winch trolley.

[0218] An aspect of the invention relates to a self-climbing tower crane that is configured to be arranged on a support, e.g. a support at or near a foot of a wind turbine mast, wherein the tower crane comprises:

[0219] - a crane base configured to be placed on the support,

[0220] - tower segments which are configured to be stacked onto one another, e.g. from below, in order to erect a crane tower which is composed of the tower segments on the crane base,

[0221] - a slewable jib unit, wherein the slewable jib unit comprises:

[0222] • a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0223] • a lifting jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a first luffing assembly

[0224] • optionally, a counter jib mounted to the crane housing, e.g. pivotally mounted to the crane housing around a lifting jib pivot axis to be pivoted by a second luffing assembly and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another, e.g. from below to lengthen the crane tower under the slewable jib unit, wherein the tower crane has a hoisting winch and an associated hoisting cable which depends from a hoisting sheave assembly on the lifting jib,

[0225] - a blade lifting tool configured to engage a wind turbine blade, wherein tower segments are each provided with a blade manipulator trolley track which extends along the length of the tower segment, such that a continuous blade manipulator trolley track is formed along the length of the crane tower, and wherein the tower crane further comprises a blade manipulator assembly comprising: a blade manipulator trolley configured to engage the blade manipulator trolley track and being movable along the track in vertical direction, a blade manipulator trolley drive for moving the blade manipulator trolley along the blade manipulator trolley track, a blade manipulator which is configured to engage the blade lifting tool, wherein the blade manipulator is supported by the blade manipulator trolley and configured to provide controlled motion in one or more degrees of freedom of the blade lifting tool and the blade engaged thereby.

[0226] In an embodiment, the blade manipulator comprises: a lateral guide bracket which is connected to the blade manipulator trolley, an axial guide bracket which is mounted on and movable, in the lateral direction of the blade, along the lateral guide bracket, an engagement member configured to be engaged with the blade lifting tool wherein the engagement member is mounted on and movable, in the axial direction of the blade, along the axial guide member.

[0227] In an embodiment, the blade manipulator assembly comprises an actuating assembly and an associated positioning system configured and to be operated to position the root end of the blade when attaching the blade to the hub, e.g. the actuating assembly comprising a lateral and axial drive to move the axial guide in the lateral direction and to move the engagement member in the lateral direction respectively.

[0228] In an embodiment, the blade manipulator assembly further comprises one or more, preferably three, manipulator winches and associated manipulator cable(s), wherein the manipulator winches are arranged on the blade manipulator, preferably on the engagement member, wherein the manipulator cable(s) is / are configured to be extended between the manipulator winch(es) and the blade lifting tool allowing to pull the blade lifting tool towards and into engagement with the blade manipulator. For example, a method is performed wherein the hoisting winch is used to pick-up the wind turbine blade held by the blade lifting tool from a vessel, e.g. dedicated blade supply vessel, present adjacent the offshore wind turbine, wherein the one or more manipulator cables are connected to the blade lifting tool, and wherein the blade is first lifted clear from the vessel and then the one or more manipulator cables are reeled in so as to bring the blade lifting tool towards and into engagement with the engagement member of the blade manipulator. For example, the blade to be lifted is initially held on the vessel by a motion compensated platform, e.g. a heave compensated platform.

[0229] In an embodiment, the counter jib is present in the slewable jib unit.

[0230] In an embodiment, a counter ballast is mounted on the counter jib, e.g. at the outer end of the counter jib. In another embodiment, a counter ballast action is created as the tower crane is provided with a counter cable and an associated counter winch, wherein the counter cable is reeved so as to exert a mechanical load on the counter jib. In the latter embodiment, preferably, also the counter winch is mounted on the winch trolley.

[0231] An aspect of the invention relates to a tower crane which comprises a blade manipulator assembly comprising: a blade manipulator trolley configured to engage a blade manipulator trolley track and being movable along the track in vertical direction, a blade manipulator trolley drive for moving the blade manipulator trolley along the blade manipulator trolley track, a blade manipulator which is configured to engage the blade lifting tool, wherein the blade manipulator is supported by the blade manipulator trolley and configured to provide controlled motion in one or more degrees of freedom of the blade lifting tool and the blade engaged thereby, wherein the blade manipulator assembly further comprises one or more, preferably three, manipulator winches and associated manipulator cable(s), wherein the manipulator winch(es) is / are arranged on the blade manipulator, preferably on the engagement member, wherein the manipulator cable(s) is / are configured to be extended between the manipulator winch(es) and a blade lifting tool allowing to pull the blade lifting tool towards and into engagement with the blade manipulator.

[0232] The present invention also relates to the installation of a wind turbine blade on a horizontal axis rotational hub of a wind turbine, e.g. on land or offshore, the wind turbine comprising a wind turbine mast and a nacelle with a horizontal axis rotational hub provided on the top end of the wind turbine mast, wherein use is made of a tower crane, e.g. a tower crane as described herein, comprising a hoisting cable and a hoisting winch, wherein the tower crane comprises a blade manipulator trolley which is configured to move along the height of the tower crane between a lower position and a blade installation position, wherein the method comprises lifting a blade to be installed to a blade installation position and attaching the blade that has been lifted to the blade installation position to the horizontal axis rotational hub of the wind turbine, wherein the wind turbine blade is suspended from the hoisting cable by a blade lifting tool, wherein the method comprises:

[0233] - bringing the blade manipulator trolley in the lower position thereof,

[0234] - bringing the blade lifting tool in engagement with the blade manipulator in the lower position thereof, e.g. using the one or more manipulator winches and associated manipulator cable(s),

[0235] - lifting the wind turbine blade to the blade installation position by operating the hoisting winch and simultaneously moving the blade manipulator trolley along the height of the tower crane, e.g. by the blade manipulator trolley drive, wherein the blade manipulator and the blade lifting tool stay in constant engagement with each other, wherein, optionally, the blade manipulator and the blade lifting tool are brought in engagement with each other by operating the one or more manipulator winches.

[0236] In an embodiment, the hoist system of the tower crane comprising the hoisting cable, hoisting winch, and the blade lifting tool, is used to pick-up the blade directly from a vessel, e.g. dedicated blade supply vessel, wherein the blade is held on the vessel by means of a motion compensated platform, e.g. a heave compensated platform, so that the blade can be held in a motion compensated mode before the hoist system is engaged with the blade for its pick-up, e.g. using the blade lifting tool, wherein preferably, the blade is then first lifted to clear the vessel, or platform thereof, and only then brought into engagement with the blade manipulator, e.g. by reeling in the one or more blade manipulator cables.

[0237] The present invention also relates to a method for installation of a wind turbine blade on a wind turbine, e.g. an offshore wind turbine, wherein use is made of the tower crane as described herein.

[0238] The present invention also relates to a foundation for a wind turbine, e.g. a monopile, or a wind turbine mast with two trunnions arranged at diametrically opposed positions. The two trunnions are interconnected by a trunnion beam extending transverse through the foundation, e.g. the monopile, or the mast. For example, the trunnions are in part formed as the two outer ends of a trunnion beam, e.g. a cylindrical trunnion beam, which extends between two diametrically opposed points on the circumference of the wind turbine mast or foundation, e.g. the monopile, and the outer ends of the trunnion beam extend outward from the wind turbine mast / foundation so as to form the trunnions which are configured to support the crane base, e.g. the annular crane base.

[0239] It is noted that trunnions on the monopile and lower end of a wind turbine mast are known for hoisting the monopile or wind turbine mast by means of a crane. In the known configuration, the trunnions are each only connected to the wall of the monopile or wind turbine mast. By interconnecting the trunnions a sturdy support for the crane is provided. The beam can be provided when manufacturing the foundation, e.g. monopile, or mast. In an embodiment, the trunnion beam is installed at a later stage, e.g. after installation of the foundation, e.g. of the monopile in the seabed.

[0240] The present invention also relates to a method for installation of an offshore wind turbine, wherein a monopile is installed in the seabed having two trunnions arranged at diametrically opposed positions, and wherein a wind turbine mast is arranged on the monopile, wherein the method comprises - after installation of the monopile in the seabed and prior to arranging of the wind turbine mast thereon - the step of interconnecting the two trunnions by a trunnion beam extending transverse through the monopile.

[0241] The present invention also relates to a method for installation of an offshore wind turbine, wherein a monopile is installed in the seabed having two trunnions arranged at diametrically opposed positions and interconnected by a trunnion beam, and wherein a wind turbine mast is arranged on the monopile, e.g. wherein the trunnions are used to support the crane base of a tower crane thereon, e.g. a crane base and / or tower crane as described herein.

[0242] The present invention also relates to a tower crane, e.g. a self-climbing tower crane, configured to be erected on an offshore wind turbine which has a wind turbine mast arranged on a foundation, e.g. a monopile, a tripod, etc, which mast or foundation has two trunnions arranged at diametrically opposed positions, e.g. interconnected by a trunnion beam, wherein the tower crane comprises:

[0243] - an annular crane base having a first base segment and a second base segment, wherein the first base segment is configured to be mounted on the trunnions, and wherein the second base segment is configured to be subsequently connected to the first base segment so that the first and segment base segments encircle the mast or the foundation, e.g. the monopile,

[0244] - a crane tower configured to be supported on the crane base, e.g. on the first base segment thereof, e.g. the crane tower configured to be composed of tower segments which are configured to be stacked onto one another, e.g. from below, in order to erect the crane tower,

[0245] - a slewable jib unit, wherein the slewable jib unit comprises:

[0246] • a crane housing having a base end and a top end, wherein the base end is configured to be mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0247] • a lifting jib having an inner end and an outer end, e.g. wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis and a first luffing assembly is configured to pivot the lifting jib, e.g. between a substantially horizontal orientation and a substantially upward vertical orientation.

[0248] In embodiments, the first base segment comprises an anti-tilt support mechanism which is configured to engage the mast or foundation at a location lower than the trunnions to counteract tilting of the first base segment when supported by the trunnions, e.g. wherein the anti-tilt support mechanism comprises an actuating assembly which is configured to move an engagement pad and to bring the engagement pad into engagement with the wind turbine mast or foundation. In embodiments, the first base segment is provided with a crane tower lifting unit which is configured to perform lifting actions in the process of stacking of tower segments to compose the crane tower.

[0249] In embodiments, the first and / or the second base segment is / are configured for storage thereon of multiple tower segments in vertical orientation.

[0250] In embodiments, the first and / or the second base segment is / are provided with a transfer trolley track, and the tower crane comprises a tower segment transfer trolley which engages and is movable along the transfer trolley track, wherein the tower segment transfer trolley is configured to move a tower segment in its vertical orientation from its storage position SP to an installation position at the crane tower lifting unit.

[0251] The present invention also relates to method for erecting a tower crane, e.g. a self-climbing tower crane, on an offshore wind turbine which has a wind turbine mast arranged on a foundation, e.g. a monopile, which mast or foundation has two trunnions arranged at diametrically opposed positions e.g. interconnected by a trunnion beam, wherein the tower crane comprises:

[0252] - an annular crane base having a first base segment and a second base segment, wherein the first base segment is mounted on the trunnions, and wherein the second base segment is subsequently connected to the first base segment so that the first and segment base segments encircle the mast or the foundation,

[0253] - a crane tower configured to be supported on the crane base, e.g. on the first base segment thereof, e.g. to be composed of tower segments which are configured to be stacked onto one another, e.g. from below, in order to erect the crane tower,

[0254] - a slewable jib unit, wherein the slewable jib unit comprises:

[0255] • a crane housing having a base end and a top end, wherein the base end is configured to be mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;

[0256] • a lifting jib having an inner end and an outer end, e.g. wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis and a first luffing assembly is configured to pivot the lifting jib, e.g. between a substantially horizontal orientation and a substantially upward vertical orientation.

[0257] In an embodiment, the first base segment comprises an anti-tilt support mechanism which is brought into engagement with the mast or foundation, e.g. monopile, at a location lower than the trunnions to counteract tilting of the first base segment relative to the mast or foundation when supported by the trunnions.

[0258] It will be appreciated that the crane tower according to any aspect or embodiment described herein may also further comprise one or more technical features discussed herein, e.g. in the claim set and / or with reference to examples, and / or with reference to one or more other aspects.

[0259] The present invention also relates to a horizontal stabiliser configured to engage a wind turbine mast.

[0260] The horizontal stabiliser comprises a horizontal stabiliser trolley and a base structure. The horizontal stabiliser trolley is engaged on the guide rails and configured to move along the height of the tower crane. Preferably, the guide rails are integrated with the chords of the crane tower. The base structure is arranged on the horizontal stabiliser trolley and extends along the width of the stabiliser trolley.

[0261] In an embodiment, the horizontal stabiliser comprises two arms which extend from the base structure and wherein each arm is further provided with and a telescopic jaw.

[0262] In an embodiment, the arms are pivotably connected to the base structure in the proximity of the centre point of said structure and configured to pivot about an arm pivot axis.

[0263] In an embodiment, the telescopic jaws each comprise a base portion and a telescopic portion, wherein the telescopic portion is configured to extend relative to the base portion. The base portion is at an inner end thereof pivotably connected to the outer end of the respective arm at a pivot point and around a jaw pivot axis. The jaw pivot axes being parallel to the arm pivot axes.

[0264] In an embodiment, each arm is provided with an arm cylinder. The arm cylinders are pivotably connected to the base structure, preferably the outer end of the base structure, at one end thereof and at the other end thereof pivotably connected to the outer end of the arm, or more preferably to the pivot point where the respective arm and jaw are connected. The arm cylinders are configured to pivot the arms around the arm pivot axis with respect to the base structure. In an embodiment, each telescopic jaw is provided with a jaw cylinder, which is at one end thereof pivotably connected to the respective arm and at the other end pivotably connected to the base portion of the jaw, preferably the inner end thereof. The jaw cylinders being configured to pivot the telescopic jaw around the jaw pivot axis with respect to the respective arm. The jaw pivot axes being parallel with the arm pivot axes.

[0265] In an embodiment, the telescopic jaws are provided with telescopic cylinders configured to extend the telescopic portion with respect to the base portion of the telescopic jaws.

[0266] In an embodiment, the horizontal stabiliser is further provided with engagement pad assemblies, which are configured to engage the wind turbine mast. Preferably, two or more engagement pad assemblies are provided, more preferably four engagement pad assemblies are provided.

[0267] In an embodiment, the outer ends of the telescopic portions are provided with an engagement pad assembly, wherein the engagement pad assembly is pivotably connected to the outer end of the telescopic portions around an engagement pad pivot axis.

[0268] In an embodiment, two engagement pad assemblies are connected at the pivot point and around a respective engagement pad pivot axis, such that the jaw pivot axes and the engagement pad pivot axes coincide.

[0269] In an embodiment, the engagement pad assemblies comprise a vertical structure which is pivotably connected to either the pivot point or the outer end of the telescopic portion. Multiple horizontal rows of engagement pads are provided along the height of the vertical structure. As shown, two horizontal rows, each comprising four engagement pads, are provided at an upper end of the vertical structure, and two horizontal rows are provided at the lower end of the vertical structure.

[0270] The telescopic jaws in combination with the pivotably connected arms, jaws, cylinders and engagement pads, allows the horizontal stabiliser to engage wind turbine masts of different diameters, e.g. wind turbines with a diameter between 3 to 12 meters in diameter. This is especially beneficial since the horizontal stabilisers travel along the height of the tower crane and engage the wind turbine mast at different heights thereof, and most wind turbines have a varying diameter along their height, e.g. the wind turbine mast having a larger diameter at the lower end thereof which gradually decreases towards the upper end of the wind turbine. It also allows the horizontal stabilisers to be used for different sized wind turbine masts. In an embodiment, the base structure is pivotably connected to the horizontal stabiliser trolley around a horizontal pivot axis. This allows the horizontal stabiliser to be pivoted from a substantial horizontal engagement position, wherein the engagement pads can engage the wind turbine mast, and a substantial vertical storage position.

[0271] It is envisaged that the horizontal stabilisers are connected to a tower crane segment prior to the tower segment being connected to the already assembled tower crane. The vertical storage position of the horizontal stabiliser allows the stabiliser to be substantially parallel to the tower segment and the wind turbine mast, taking up less space and making it easier to transfer the tower segment with the horizontal stabiliser attached to the installation position thereof. For example, a horizontal stabiliser is connected to one of the tower segments that are stored on the crane base, for the assembly of an offshore wind turbine. The vertical storage position allows the horizontal stabiliser to be stored on the base.

[0272] In practical embodiments, the tower crane has one crane tower, one crane tower lifting unit, and one jib unit as discussed herein. In another embodiment, it is envisaged that two crane towers with jib units are erected along opposite sides of a wind turbine mast, e.g. allowing for tandem lifting of a wind turbine component, e.g. a heavy component, e.g. a nacelle or a rotor assembly with rotor blades. The two crane towers may be arranged on one common crane base.

[0273] The inventions and various embodiment, optional details, and aspects will now be explained with reference to the drawings. In the drawings:

[0274] Fig. 1 shows a schematic view of the tower crane,

[0275] Fig. 2 shows a schematic view of the tower crane and crane tower lifting unit,

[0276] Figs. 3a - d show the steps of the tower crane assembly method,

[0277] Figs. 4a - e show the steps of crane tower assembly phase,

[0278] Figs. 5a - h show an alternative embodiment of the tower crane and the steps of an alternative tower crane assembly method,

[0279] Figs. 6a - c show the steps of the installation of the stabiliser devices,

[0280] Figs. 7a, b show the tower crane mounted on an offshore wind turbine,

[0281] Figs. 8a, b show the tower crane installing a blade on an offshore wind turbine using the blade manipulator assembly,

[0282] Fig. 9 shows a close up view of the top end of the tower crane,

[0283] Figs. 10a, 10b, 11 show the tower crane lifting a blade from a vessel,

[0284] Figs. 12a - e show the horizontal stabilisers, Fig. 13 shows the base segments mounted on the wind turbine mast or monopile,

[0285] Fig. 14 shows the support mechanism of the first base segment,

[0286] Figs. 15a - e show the mounting of the crane base on a wind turbine mast,

[0287] Fig. 16 shows a monopile with a trunnion beam interconnecting diametrically opposed trunnions,

[0288] Figs. 17a, 17b schematically show a jack-up vessel with a tower crane according to the invention,

[0289] Fig. 17c schematically shows the jack-up vessel provided with a movable cantilever on which a tower crane according to the invention is arranged.

[0290] Figure 1 shows a self-climbing tower crane 1 that is configured to be arranged on a support at a hoisting site, e.g. at a foot of a wind turbine mast.

[0291] The tower crane 1 comprises:

[0292] - a crane base 8 configured to be placed on the support at the hoisting site,

[0293] - tower segments 3,4 which are configured to be stacked onto one another from below in order to erect a crane tower 2 which is composed of the tower segments 3,4 on the crane base 8,

[0294] - a crane tower lifting unit 10 which is configured to be mounted on the crane base 8, and wherein the crane tower lifting unit 10 is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit 10 stepwise lifts the crane tower 2 from below,

[0295] - a slewable jib unit 100.

[0296] The slewable jib unit 100 comprises:

[0297] • a crane housing 110 having a base end 111 and a top end 112, wherein the base end 111 is mounted on top of the crane tower 2, and wherein the crane housing 110 is provided with a slew bearing 113;

[0298] • a lifting jib 120 having an inner end 120a and an outer end 120b, wherein the inner end 120a is pivotally mounted to a front section of the crane housing 110 around a lifting jib pivot axis, and wherein the lifting jib 120 is further provided with a first luffing assembly 121 which is configured to pivot the lifting jib 120 between a substantially horizontal orientation, shown in Fig. 4d, and a substantially vertical upward orientation, shown in Fig. 3d and Fig. 4c;

[0299] • a counter jib 130 having an inner end 130a and an outer end 130b, wherein the inner end 130a is pivotally mounted to a back section of the crane housing 110 around a counter jib pivot axis, and wherein the outer end 130b is provided with a counter ballast 132, and wherein the counter jib 130 is further provided with a second luffing assembly 131 which is configured to pivot the counter jib 130 between a substantially horizontal orientation, shown in Fig. 1 , and a substantially vertical upward orientation shown in Fig. 3d in Fig. 4c.

[0300] The tower crane 1 is configured to - with the slewable jib unit 100 connected to a tower segment 3, 4 - erect the crane tower 2 by stacking the tower segments 3,4 onto one another from below to lengthen the crane tower under the slewable jib unit 100.

[0301] As shown in Figure 3d and 4c, the lifting jib and counter jib can be simultaneously in the vertical upward orientation.

[0302] The crane tower 2 comprises a lower section 2a and an upper section 2b. The upper section 2b is composed of a series of multiple upper tower segments 4 and the lower section 2a is composed of a series of multiple lower tower segments 3. The lower section 2a supports the upper section 2b thereon. The upper and lower tower segments 3, 4 are embodied as tubular girder type tower segments, and wherein the upper and lower end portions of the upper and lower tower segments are provided with connectors 5 to rigidly interconnect the tower segments 3,4.

[0303] The crane tower 2 has a lower stabiliser device 20 and an upper stabiliser device 21, which are configured to horizontally connect to the crane tower 2 to a wind turbine mast 210. The upper stabiliser device is connected to the upper portion 2b of the crane tower 2, and the lower stabiliser device is connected to a lower portion 2a of the crane tower 2.

[0304] In an embodiment, the upper stabiliser device 20 is configured to travel up and down along the upper section of the crane tower 2.

[0305] In an embodiment, the tower segments 210a, at least at the upper portion of the crane tower 2, are each provided with at least one guide rail extending along the height of the upper tower segment such that the guide rails of the interconnected upper tower segments form a substantially continuous guide rail. The one or more stabiliser devices are configured to move along the continuous guide rail up and down the crane tower.

[0306] In an embodiment, the crane is provided with an upper stabiliser hoist devices 22 arranged at the top end of the crane tower 2 and which is configured to hoist the one or more stabiliser devices along the crane tower. In the shown embodiment, the crane housing 110 comprises a lower and an upper crane housing section 111 , 112. The lower crane housing section 111 is mounted on top of the crane tower 2 and wherein the crane housing 110 further comprises a slew bearing 113 which is provided between the lower and upper crane housing section 111 , 112 and which allows the upper crane housing section 112 to slew relative to the lower crane housing section 110a and the crane tower 2.

[0307] The upper crane housing section 112 comprises a base 112a and a vertical housing column 112b. The vertical housing column 112b having a base end and a top end. At the top end, the vertical housing column 112b is provided with a luffing sheave assembly 140, and wherein the base and the vertical housing column are configured to be connected to each other.

[0308] In the shown embodiment, the first and second luffing assemblies 121, 131 each comprise: o the luffing sheave assembly 140 which is arranged at or near the top end of the crane housing 110; o a luffing winch and associated luffing cable.

[0309] The luffing cable of the first luffing assembly 121 is guided via the respective luffing sheave assembly 140 to the outer end of the lifting jib 120b, which enables pivoting of the lifting jib 120 about the lifting jib pivot axis. The luffing cable of the second luffing assembly 131 is guided via the respective luffing sheave assembly 140 to the outer end of the counter jib 130b, to enable pivoting of the counter jib 130 about the counter jib pivot axis.

[0310] In an embodiment, the luffing winches are arranged inside of the upper crane housing section 112.

[0311] As shown in Figure 1 , the hoisting winch 30 is arranged at the crane base 8 of the tower crane 1. The hoisting cable 31 extending from the hoisting winch 30 along a side of the crane tower 2 into the crane housing 110 and wherein the hoisting cable extends from the crane housing 110 to a hoisting sheave assembly 122 arranged at the outer end of the lifting jib 120b, and wherein the hoisting cable extends between the hoisting sheave assembly 122 to a load connector 123 in a multi-fall arrangement.

[0312] Figure 2 shows an embodiment of the crane tower lifting unit 10, which comprises a vertical lifting column 11 and a base 8. The vertical lifting column 11 comprises a base end 11a and a top end 11b, wherein the vertical lifting column 11 is pivotable between a horizontal position, shown in Figure 3b-c and a vertical position, shown in Figure 2, relative to the base 8. The crane tower lifting unit 10 further comprises a lifting tool 13 which engages the tower segment 4 at a lower end thereof and a hoisting assembly. The hoisting assembly comprises one or more hoisting winches, not shown, and associated hoisting cables 14 which are connected to the lifting tool 13 and a hoisting sheave assembly 15 arranged at or near the top end 11b of the vertical lifting column 11, wherein the hoisting cable 14 is guided via the hoisting sheave assembly 15 to the lifting tool 13.

[0313] In an embodiment, the vertical lifting column 11 of the crane tower lifting unit 10 is provided with a track which extends between the base end 11a and the top end 11b of the vertical lifting column 11, such that the lifting tool 10 is movable along the track and thus along the vertical lifting column 11.

[0314] In the shown embodiment, the crane tower lifting unit 10 is provided with a tower segment transfer trolley 16 which is horizontally movable, between a storage position, shown in Figure 2 and an installation position. The tower segment transfer trolley 16 is provided with mounting members 17 on which a tower segment 210a can be mounted. The tower segment transfer trolley 16 is configured to move the tower segment 210a from the storage position to the installation position where the tower segment is positioned underneath and aligned with the lifted crane tower.

[0315] In figures 3a-d, steps of the method for erecting a tower crane are shown.

[0316] Figure 3a shows the crane base 8 placed on a support at a hoisting site adjacent the foot of a wind turbine mast.

[0317] Figure 3b shows the crane tower lifting unit 10 mounted on the crane base 8, wherein the crane lifting unit 10 is horizontally orientated and the crane lifting unit 10 is pivotable relative to the crane base 8.

[0318] Figure 3c shows the slewable lifting jib unit 100 being lifted by an auxiliary crane onto the vertical lifting unit 10, wherein both the slewable jib unit 100 and the vertical lifting unit are horizontally orientated, and wherein the slewable jib unit 10 lies along the vertical lifting column 11 of the crane tower lifting unit 10.

[0319] Figure 3d shows the interconnected slewable lifting jib unit 100 and vertical lifting unit 10 being lifted by an auxiliary crane 200 from a horizontal orientation to a vertical orientation. The lifting jib and the counter jib are in the substantially vertical orientation during the crane tower assembly phase, see also fig. 4c.

[0320] Figures 4a - d show the crane tower assembly phase, in which - with the crane tower lifting unit 10 in vertical orientation - the crane tower 2 is erected by stacking one or more tower segments one-by-one from below under the slewable lifting jib unit 100 to form the crane tower, in which crane tower assembly phase the crane tower lifting unit 10 lifts the already assembled part of the crane tower 2.

[0321] In the shown embodiment, the tower crane 1 is assembled and simultaneously used to construct a wind turbine mast 210 at a hoisting site, wherein the wind turbine mast 210 comprises multiple segments 210a which are configured to be stacked onto one another from above.

[0322] Figure 4a shows the tower crane 1 wherein two upper tower segments 4 are installed underneath the slewable lifting jib unit 100, wherein the lifting jib 120 is used to install the first wind turbine mast segment 210a at the hoisting site. The counter jib 130 is in an intermediate position between the horizontal and vertical orientation. Due to the lifting jib 120 being in an almost vertical orientation only a relatively small moment is created, which thus requires a smaller counter moment created by the counter jib 130, by being pivotable the counter jib can easier vary the counter moment it creates and can thus be easier adapted to the current lifting operation.

[0323] Figure 4b shows the partly assembled tower crane 1 and the wind turbine mast 210, wherein - once the slewable lifting unit 100 is sufficiently high - the slewable lifting unit 100 is used to lift a wind turbine mast segment 210a onto the top of the already installed wind turbine mast segments. The crane tower 2 is provided with horizontal stabiliser devices 20, 21 which engage the wind turbine mast 210.

[0324] Figure 4c shows the partly assembled tower crane 1 and the wind turbine 210, wherein the crane tower 1 is being assembled by stacking tower segments 3 one-by-one from below. The partly assemble tower crane 1 is lifted by the crane tower lifting unit 10 and a tower segment 3 is positioned below the tower crane such that the upper end of the tower segment 3 can be connected to the lower end of the assembled crane tower 2. During the process of stacking the tower segments from below, the lifting jib 120 and counter jib 130 are in the substantially vertical upward orientation, which increases the stability of the tower crane. Figure 4d shows the fully assembled tower crane 1 and wind turbine mast 210. The horizontal stabiliser devices 20, 21 have travelled along the crane tower 2. The lifting jib 120 is used to lift and install the nacelle 211 onto the top of the wind turbine mast 210, here due to the extra weight of the nacelle 211 compared to the wind turbine mast segments 210a, the counter jib 130 has been moved from the vertical orientation shown in Figure 4c to the horizontal orientation to counter act the larger moment.

[0325] Figure 4e shows the lifting jib 120 being used to lift and install a wind turbine blade 212. Here the slewable lifting jib unit 100 has been slewed to be able to lift the wind turbine blade 212. In an embodiment shown in Figure 1 , the lower tower segments 3 each have inner lower tower segments 3a and outer lower tower segment 3b, the inner lower tower segment having a longitudinal axis. The outer lower tower segment 3b telescopically envelopes the inner lower tower segment 3a so as to be movable along the longitudinal axis of the inner lower tower segment between a retracted and an extended position.

[0326] In an embodiment, the crane tower lifting unit is used to install and extend the lower tower segment 3. The method comprising the following steps:

[0327] - connecting the upper portion of the outer lower tower segment 3b to the lifted tower crane 1 , wherein the outer lower tower segment 3b is in the retracted position;

[0328] - engaging the lifting tool 13 to the lower portion of the outer lower tower segment 3b;

[0329] - moving the outer lower tower segment 3b from the retracted position to the extended position;

[0330] - locking the outer lower tower segment 3b relative to inner lower tower segment 3a.

[0331] The top end of the inner lower tower segment 3a and a base end of the outer lower tower segment 3b are provided with cooperating locking members 3c, which are used for securing the inner lower tower segment 3a and outer lower tower segment 3b relative to each other when the outer lower tower segment 3b is in the extended position.

[0332] The connectors 3c of the inner and outer lower tower segments 3a, b are embodied as rectangular connector members. The connector members 3c of the inner and outer lower tower segments 3a, b are provided at each corner thereof with cooperating connection elements, such that the lower tower segments 3 can be rigidly interconnected.

[0333] Figures 5a - h shows an alternative embodiment of the tower crane and an alternative method of assembling said tower. The upper crane housing section 312 comprises a base 312a and a vertical housing column 312b, the vertical housing column having a lower end and a top end, wherein at the top end the vertical housing column is provided with a luffing sheave assembly 140, and wherein the base and the vertical housing column are configured to be connected to each other.

[0334] The lifting jib 320 comprises a first and second lifting jib section 321 , 322, each section having an inner end 321a, 322a and an outer end 322a, 322b, wherein the inner end 321a of the first section 321 is configured to be pivotally mounted to the upper crane housing section base 312a around a lifting jib pivot axis. The first and second lifting jib sections 321 , 322 are hingedly connected at their outer end 321b and inner end 322a respectively, such that first and second lifting jib sections 321 , 322 can pivot with respect to each other between a folded and an extended position, and wherein the outer end of the second lifting jib section is configured to receive a boom head thereon.

[0335] The counter jib 330 comprises a first and second counter jib section 331, 332, each section having an inner end 331a, 332a, and an outer end 331b, 332b, wherein the inner end 331a of the first section 331 is configured to be pivotably mounted to the crane housing base 312a around a counter jib pivot axis. The first and second counter jib sections 331 , 332 are configured to be connected to each other at their outer end 331b and inner end 332a respectively, and wherein the outer end of the second counter jib section is configured to receive a counter ballast.

[0336] The method comprises the following steps:

[0337] - placing the crane base 8 on the support at the hoisting site;

[0338] - placing the vertical housing column 10 on the crane base 8, such that the vertical housing column 11 is horizontally oriented,

[0339] - connecting the inner end 331a of the first counter jib section 331 to the lower end of the vertical housing column 312b,

[0340] - pivotally connecting the second lifting jib section 322 to the first lifting jib section 321, such that the first and second lifting jib sections 321, 322 are in the folded position, wherein the inner end of the first jib section 321a is connected to the base of the upper crane housing 312a, wherein the first and second lifting jib sections 321, 322 are in a horizontal orientation;

[0341] - pivoting the second lifting jib section 322 relative to the first lifting jib section 321 to the extended position and securing the first and second lifting jib sections 321, 322 relative to each other;

[0342] - placing the crane housing 110 and lifting jib 320 horizontally on top of the vertical housing column 10 and first counter jib section 331 , e.g. using an auxiliary crane; - mounting a boom head 230 on the outer end of the second lifting jib section 322b;

[0343] - connecting the base 312a and vertical housing column 312b to each other;

[0344] - connecting the lower crane housing 111 to the lifting tool 13 of the crane tower lifting unit 10;

[0345] - pivoting the crane tower lifting unit 10 from a horizontal orientation to a vertical orientation, such that the jib unit 300 is also moved to a vertical orientation, wherein the lifting jib 320 and counter jib 330 are in the substantially vertical position;

[0346] - lifting the jib unit 300 with the lifting tool 13 of the crane tower lifting unit, such that a first upper tower segment 4 can be connected to the base end 111 of the slewing jib unit 100;

[0347] - pivoting the first counter jib section 331 from the vertical position to the horizontal position;

[0348] - connecting the second counter jib section 332 to the first counter jib section 331.

[0349] The method further comprises a crane tower assembly phase, in which - with the crane tower lifting unit 10 in vertical orientation - the crane tower 2 is erected by stacking one or more tower segments one-by-one from below under the slewable lifting jib unit to form the crane tower, in which crane tower assembly phase the crane tower lifting unit lifts the already assembled part of the crane tower.

[0350] Figures 6a-c shows the steps of the installation of the stabiliser device 21 on the crane tower. The stabiliser device 21 is configured to connect the crane tower the wind turbine mast, wherein the stabiliser device clamps onto the wind turbine mast. The stabiliser device comprises a crane tower portion 21a and a clamping portion, wherein the crane tower portion 21a and the clamping portion 21b are pivotably connected such that the clamping portion can be moved between a horizontal operational position and a vertical mounting position.

[0351] Figure 6a shows the stabiliser device in the vertical mounting position, wherein the clamping portion 21b is vertically orientated with respect to the crane tower portion 21a. The stabiliser device is positioned between the wind turbine mast and the crane tower, such that the tower crane portion 21a can be connected to the crane tower.

[0352] Figure 6b shows the stabiliser device in the horizontal operational position, wherein the clamping portion 21b has been pivoted from the vertical orientation to a horizontal position, such that the clamping portion 21b can engage the wind turbine mast. Figure 6c shows the stabiliser device having been moved to a higher position. The stabiliser device is mounted on the continuous guide rails and connected to a stabiliser hoist device 15 which is arranged at the top of the crane tower., wherein the stabiliser hoist device hoists the stabiliser device which moves along the continuous guide rail.

[0353] Figure 7a shows an offshore wind turbine 1000.

[0354] The offshore wind turbine comprises a wind turbine mast 1001, a nacelle 1002 with a horizontal axis rotational hub 1003 provided at the top end of the wind turbine mast 1001. The offshore wind turbine 1000 is further provided with three wind turbine blades 1004. Here two blades are already installed, and the third blade is being installed on the horizontal axis rotational hub 1003 by use of an embodiment of the inventive tower crane.

[0355] The wind turbine mast 1001 is supported on an offshore foundation, here on a floating foundation 1010. In another embodiment, the mast 1001 can be mounted on a monopile foundation, a tripod foundation, or a jacket type foundation.

[0356] The floating foundation 1010 comprises one or more, here three interconnected, stabilising columns 1011 , wherein one stabilising column 1011 is provided with a mast mounting structure on which the wind turbine mast 1001 is mounted. Other floating foundations, e.g. a spar buoy, are envisaged as well.

[0357] The tower crane 1100 is being used to install a wind turbine blade 1004 to the horizontal axis rotational hub 1003.

[0358] The tower crane 1100 has an annular crane base 1110 which is mounted on the lower portion of the wind turbine mast 1001. The annular crane base 1110 is, in this example, mounted on supporting brackets which are provided on the lower portion of the wind turbine mast 1001 or on the foundation.

[0359] The annular crane base 1110 encircles the lower part of the wind turbine mast 1001.

[0360] The crane tower 1101 has been erected along the wind turbine mast 1001 and is supported on the annular crane base 1110.

[0361] The crane tower 1101 is composed of six tower segments 1102 which are stacked onto one another from below in order to erect the crane tower 1101. For example, each crane tower segment 1102 is between 20 and 30 meters high, e.g. about 25 meters. In this example, all segments 1102 are the same.

[0362] All tower segments 1102 are embodied as tubular girder type tower segments and are provided with connectors at their ends to rigidly interconnect the tower segments.

[0363] The tower crane 1100 is provided with two horizontal stabilisers 1140 that is configured to be moved along the crane tower 1101 and engage the wind turbine mast, e.g. having clamping portions which clamp onto the exterior of the mast 1001.

[0364] The height of the crane tower 1101 erected on the annular crane base is between 100 - 200 meters high, preferably between 120 - 180 meters. Each tower segment having a height of between 20 - 30 meters, preferably 25 meters.

[0365] The tower crane 1100 is further provided with a slewable jib unit 1103. The slewable jib unit comprises:

[0366] • a crane housing 1104 having a base end and a top end, wherein the base end is mounted on top of the crane tower 1101, and wherein the crane housing is provided with a slew bearing;

[0367] • a lifting jib 1105 having an inner end and an outer end, wherein the inner end is pivotally mounted to the slewable part of the crane housing 1104 around a lifting jib pivot axis, and a first luffing cylinder 1105a which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;

[0368] • a counter jib 1106 having an inner end and an outer end, wherein the inner end is pivotally mounted to the slewable part of the crane housing around a counter jib pivot axis, and wherein the counter jib, e.g. at the outer end thereof, is provided with counter cable 1107, and a second luffing cylinder 1106a which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation.

[0369] The first luffing cylinder 1105a is at one end connected to the top end of the crane housing 1104 and the other end of the first luffing cylinder 1105a is connected to the lifting jib 1105.

[0370] The second luffing cylinder 1106a is at one end connected to the top end of the crane housing 1104 and the other end of the second luffing cylinder 1106a is connected to the counter jib 1106. The first and second lifting cylinders 1105a, 1106a are configured to pivot the lifting jib 1105 and the counter jib 1106 respectively from the substantially horizontal orientation and the substantially vertical upward orientation.

[0371] As shown, preferably, the luffing cylinders may be provided in pairs of cylinders.

[0372] The counter jib 1106 is at the outer end thereof provided with a counter cable 1107. The counter cable 1107 extends from the outer end of the counter jib 1106 to a counter winch 1109 arranged on the crane base 1110. This may be a single cable fall arrangement, or a multi-fall arrangement. It is noted that a multi-fall arrangement requires a significant capacity of the winch drum, or a traction winch is used in conjunction with a cable storage drum for storage of the counter cable, e.g. the cable storage drum being arranged elsewhere on the crane base.

[0373] The tower crane 1100 has a crane tower lifting unit 1108, shown in Figure 8, which is mounted on the annular crane base 1110. The crane tower lifting unit 1108 being configured to perform lifting actions in the process of stacking of the tower segments 1102. The crane tower lifting unit 1108 stepwise lifts the crane tower 1101 from below.

[0374] The annular crane base comprises a first base segment 1110a and a second base segment 1110b which are connected to each other. As shown in Figure 13 the first and second base segments 1110a, 1110b are connected to each other by multiple pin-hole connections.

[0375] The base segments 1110a, 1110b comprise cooperating connection members, which engage each other and connect the two base segments. Each base segment 1110a, 1110b is provided with two connection members at each end thereof.

[0376] Figure 13 shows the first and second base segments 1110a, 1110b.

[0377] The wind turbine mast or monopile 1001 has support brackets, here embodies as two trunnions 1150 which are arranged at diametrically opposed positions at the lower end of the wind turbine mast or on the monopile 1001. The trunnions 1150 may be configured to be engaged during the upending and / or lifting of the wind turbine mast or monopile.

[0378] As shown in Figure 16, the trunnions 1150 are interconnected by a trunnion beam 1150a extending transverse through the mast, e.g. at the lower end thereof, or the monopile 1001. In this example, the trunnions are in part formed as the two outer ends of a cylindrical trunnion beam 1150a which extends between two diametrically opposed points on the circumference of the wind turbine mast 1001. The outer ends of the trunnion beam 1150a extend outward from the wind turbine mast or monopile as to form the trunnions which are configured to support the annular crane base.

[0379] The semi-circular first base segment 1110a has a support structure 1151 which engages on the two trunnions 1150.

[0380] The support structure 1151 comprises two support members 1152 which are each configured to receive one of the trunnions 1150, such that the first base segment 1110a is supported by the two trunnions 1150.

[0381] As shown in Figures 15a - d, the support members 1152 each have a receiving space which is configured to receive the respective trunnion, such that the first base segment is supported by the trunnions 1150. The support members 1152 further comprises a guiding structure, e.g. a funnel to facilitate lowering the first base segment onto the trunnions.

[0382] As shown in Figure 14, the first base segment 1110a further comprise an anti-tilt support mechanism 1153 which supports the first base segment 1110a combined with the support structure 1151 on the wind turbine mast or foundation, e.g. monopile, 1001 at a location lower than the support brackets / trunnions. The anti-tilt support mechanism 1153 engages the wind turbine mast or foundation 1001 and prevents tilting of the first base segment 1110a relative to the wind turbine mast or foundation 1001.

[0383] The anti-tilt support mechanism 1153 has an engagement pad 1154 which engages the wind turbine mast or foundation 1001. The engagement pad 1154 is arranged on a mobile engagement frame. In this example, the pad 1154 is arranged at a lower end of an engagement frame 1155 which is pivotably connected to the first base segment 1110a at a frame connection point 1156 and extends downward from the first base segment 1110a.

[0384] The anti-tilt support mechanism 1153 further comprises an actuating assembly 1157 which is configured to move the engagement pad 1154 in order to bring the engagement pad 1154 into engagement with the wind turbine mast or foundation 1001. The actuating assembly1157 here comprises a first rod 1158 which is at one end pivotably connected to a lower side of the first base segment 1110a, and a second rod 1159 which is pivotably connected to a lower end of the first rod 1158 at a rod connection point 1160. The second rod 1159 is at the other end pivotably connected to the lower end of the engagement frame 1155. The actuating assembly further comprises one or more actuating cylinders 1161 which extend from the lower end of the first base segment 1110a to the rod connection point 1160. By retracting the one or more actuating cylinders 1161 the engagement frame 1155 is rotated around the connection point 1160.

[0385] As shown in Figures 15a-c and Fig. 15e, when the one or more actuating cylinders 1161 are extended, the first and second rods 1158, 1159 define a first angle b1 smaller than 180 degrees. As shown in Figure 15d, once the one or more actuating cylinders 1161 are retracted - the first angle b1 is larger than 180 degrees. By having a first angle which is larger than 180 degrees it ensures that, without extending the one or more cylinders, the engagement pad remains engaged with the wind turbine mast.

[0386] As shown in Figure 7b, the tower segments 1102 are arranged in their vertical orientation and side by side at respective storage positions on the crane base, here in an array extending over an arc-segment of the annular crane base 1110. The tower crane has a transfer device for the tower segment which is configured and operated to move the tower segments in succession from their respective storage position ST to the position where the tower segment is assembled with the crane mast 1101.

[0387] The tower segments 1102 are all stored on the second base segment 1110a while the crane lifting unit 1108 is provided on the first base segment.

[0388] As shown in Figure 13, the second base segment 1110b is provided with storage members 1115 which correspond to a storage position SP of the tower segments 1102, the storage members 1115 are configured to securely retain and store the tower segments on the second base segment 1110b until the tower segment 1102 is moved to the installation position IP by the transfer trolley 1111.

[0389] The storage members 1115 are here shown as four pin hole connectors for each storage position SP which are configured to facilitate a pin-hole connection with the lower end of the tower segments.

[0390] A tower segment transfer trolley 1111 is arranged on the crane base 1110. The transfer trolley 1111 engages on a tower segment, e.g. at the lower end thereof, e.g. engages connectors at said end, and moves the tower segment 1102 in its vertical orientation from its storage position SP to the installation position IP below and aligned with the lifted crane tower 1101.

[0391] The tower segment transfer trolley 1111 engages and moves along a transfer trolley track 1112 which is (semi-)circular and here extends along the annular crane base 1110. The transfer trolley 1111 is able to move along the trolley track 1112 between the storage position(s) SP of the tower segment 1101 to the installation position IT at the crane tower lifting unit 1108. For example, the trolley 1111 has a drive motor, e.g. a rack and pinion drive arrangement.

[0392] Each of the base segments 1110a, 1110b is provided with a transfer trolley track 1112, which forms a substantially continuous transfer trolley track 1112 along which the tower segment transfer trolley 1111 can move when the two segments 1110a, 1110b are connected to each other.

[0393] The hoisting cable 1120 extends from the hoisting winch 1121 in a single fall to a counter jib sheave assembly 1122 provided at the outer end of the counter jib 1106. The hoisting cable 1120 extends from the counter jib sheave assembly 1122 to a crane housing sheave assembly 1123 provided at the top end of the crane housing 1104. From the crane housing sheave assembly 1123 the hoisting cable extends to a lifting jib sheave assembly 1124 provided at the outer end of the lifting jib 1105. The hoisting cable then extends from the lifting jib sheave assembly 1124 to the blade lifting tool 1125.

[0394] In view of the weight of the tool 1125 and the blade to be lifted, which blade may weigh more than 50 tonnes, the hoisting cable 1120 extends in a multi-fall arrangement, here a 4-fall arrangement, between the blade lifting tool 1125 and the lifting jib sheave assembly 1124.

[0395] Due to the multi-fall arrangement, the winch 1121 has a significant cable storage capacity on the drum.

[0396] The counter cable 1107 extends from the counter winch 1109 to the counter jib sheave assembly 1122 provided at the outer end of the counter jib 1106. From there the cable 1107 extends in a multi-fall arrangement via the crane housing sheave assembly 1123 to the lifting jib sheave assembly 1124, and, in this example, down to a dead end near the counter winch 1109.

[0397] The tower crane 1100 is provided with a winch trolley 1113. The hoisting winch 1121 and the counter cable winch 1109 are mounted on the winch trolley 1113. In this example, the dead end of the counter cable is also mounted on the winch trolley 1113. The winch trolley 1113 is engaged with and is configured to move along a winch trolley track 1114 which is provided on the crane base 1110. The circular winch trolley track 1114 extends along the crane base 1110.

[0398] The winch trolley 1113 allows the hoisting winch 1121 and counter cable winch 1109 to move along with the counter jib 1106 when the slewable jib unit 1103 is slewing, e.g. by a drive of the winch trolley. This design ensures that the hoisting cable and counter cable can remain substantially vertical.

[0399] Each semi-circular crane base segment 1110a, 1110b is provided with a part of the winch trolley track 1114 which parts from a substantially continuous winch trolley track 1114 when the two semi-circular segments are connected to each other.

[0400] The segment transfer trolley track 1112 and the winch trolley track 1114 may be formed by one or more (semi-)circular rails which extend along the crane base 1110 along which both the transfer and winch trolley 1111, 1113 can move, e.g. along the entire crane base.

[0401] The wind turbine blade 1104 is suspended from the hoist cable 1120 by a blade lifting tool 1125.

[0402] The tool 1125 is configured to hold the blade at least in a horizontal orientation. The tool 1125, optionally, may be configured to tilt the blade into an inclined orientation.

[0403] The tool 1125 has an inner end that is at or near the root of the blade and an outer end that is beyond the centre of gravity COG of the blade.

[0404] The hoisting cable 1120 engages on the blade lifting tool 1125 in vertical alignment with the centre of gravity COG of the blade so that the blade is effectively engaged at the centre of gravity thereof by the tool 1125.

[0405] Each tower segment 1102 is provided with blade manipulator trolley track 1130 on the opposite side relative to the guide rail(s) for the horizontal stabiliser devices.

[0406] The trolley track 1130 extends along the length of the tower segments, such that a substantially continuous blade manipulator trolley track is formed along the length of the crane tower 1101. As shown, the rails of the blade manipulator trolley track 1130 are mounted at the corners of the four-sided cross-sectional tower segments 1102.

[0407] The tower crane 1100 comprises a blade manipulator assembly 1331 comprising: a blade manipulator trolley 1132 engaging the blade manipulator trolley track 1130 and being movable along the track in vertical direction, a blade manipulator trolley drive 1133 for moving the blade manipulator trolley 1132 up and down along the track 1130, a blade manipulator 1134 which is configured to engage the blade lifting tool 1125, wherein the blade manipulator 1134 is supported by the trolley 1132 and is configured to enable controlled displacement of the blade lifting tool in one or more degrees of freedom relative to the trolley, e.g. in axial direction of the blade lifting tool and the blade held therein and in a lateral direction, perpendicular to the axial direction, e.g. both the axial and lateral direction being in a horizontal plane.

[0408] The lifting jib 1105 has a length such that the hoisting cable 1120 can engage on a horizontally oriented blade at the centre of gravity C.O.G thereof, whilst the manipulator assembly engages the lifting tool.

[0409] The blade manipulator trolley is driven up and down along the crane tower by a cable and winch drive 1133.

[0410] The crane tower 1101 and the blade manipulator trolley track 1130 extend above or level to the horizontal axis rotational hub of the nacelle 1003, allowing the trolley 1132, the blade manipulator 1134 engaged with the blade lifting tool 1125, and the wind turbine root to be level with the rotational hub of the nacelle, allowing the blade to be horizontally installed on the nacelle, wherein use is made of the functionality of the blade manipulator, e.g. to effect accurate alignment of the blade root with the respective blade mounting structure of the hub.

[0411] The blade 1004 is kept in horizontal orientation while being lifted, so that both the lower receiving position thereof and the blade installation position bip are horizontal. In embodiments, the blade lifting tool allows for some tilting of the blade out of the horizontal plane for the blade installation, e.g. into a 15 degrees inclination.

[0412] A physical link is established between the blade lifting tool and the trolley 1131. This, for example, allows for an operation wherein that the manipulator trolley is effectively driven as the tool that holds the blade is lifted by the hoist system. This link may also be of use when the blade lifting tool is to be lowered without a blade being held, wherein the link has the effect that undue sway motion of the blade lifting tool is prevented.

[0413] The blade manipulator 1134 comprises:

[0414] - a lateral guide bracket 1135 which is connected to the blade manipulator trolley 1331 ,

[0415] - an axial guide bracket 1136 which is mounted on and movable in the lateral direction of the blade along the lateral guide bracket 1135,

[0416] - an engagement member 1137 configured to be engaged with the blade lifting tool 1125 wherein the engagement member is mounted on and movable in the axial direction of the blade along the axial guide member 1136.

[0417] The blade manipulator assembly 1134 comprises an actuating assembly and an associated positioning system configured and operated to position the root end of the blade 1004 when attaching the blade to the respective blade mounting structure of the hub 1103. The actuating assembly comprises a lateral and axial drive to move the axial guide in the lateral direction and to move the engagement member in the lateral direction respectively. Preferably, the actuating assembly comprises position actuators to move the engagement member in yaw direction, and optionally in pitch direction.

[0418] The positioning system comprises one or more sensors to detect the actual position and / or motion of the blade relative to the mounting structure of the hub, e.g. during the phase of mating the blade root with the horizontal rotational hub 1003.

[0419] The actuating assembly may be configured to dampen motion(s) of the blade, e.g. to dampen any sway motion(s) in a horizontal plane

[0420] The blade manipulator assembly further comprises manipulator winches 1138 and associated manipulator cables 1139. The manipulator winches 1138 are arranged, for example, on the engagement member 1137. The manipulator cables 1139 are configured to be arranged between the manipulator winches 1139 and the blade lifting tool 1125. As shown in figure 10b, the cables 1139 are secured whilst the blade 1004 is still handled by a crane 1021 of the vessel supplying the blade 1004.

[0421] The blade manipulator assembly 1131 is already engaged to the blade manipulator track 1130 of the tower segment 1103 while the tower segment is stored on the crane base 1110. Before the crane base 1110 is mounted on the wind turbine mast 1001, the crane tower lifting unit 1108 is mounted on the first base segment 1110a , the tower segments 1102 are already stored on the second base segment 1110b, the winch trolley 1113 and tower segment transfer trolley 1111 are already engaged with the tracks 1114 provided on the base, and the slewable jib unit 1103 is already at the installation position at the crane tower lifting unit. All components of the crane tower are thus already provided on the crane base, once the crane base has been mounted on the wind turbine mast, the crane tower can assemble itself without the need of additional support, e.g. from a vessel.

[0422] The wind turbine 1000 is installed on a floating foundation 1010.

[0423] Here, by way of example, the floating foundation 1010 comprises three interconnected stabilising columns 1011 , embodied as buoyant columns. One stabilising column is provided with a mast mounting structure configured to mount the wind turbine mast thereon. Each stabilising column is provided with one or more ballast tanks for containing a ballast, e.g. a ballast liquid, e.g. ballast (sea) water. Preferably, a ballast control system is provided which is configured to move the ballast liquid between ballast tanks and / or in and out of the ballast tanks, to adjust the orientation of the floating foundation.

[0424] The ballast control system may be used to increase the buoyancy of the stabilising column 1011 provided with the mast mounting structure and the wind turbine mast, prior to the tower crane 1100 being installed on the wind turbine mast. For example, the ballast control system moves the ballast water from the ballast tanks of the stabilising column provided with the mast mounting structure to the ballast tanks of the other stabilising columns. The weight of the tower crane will be substantial, by changing the buoyance of each stabilising columns it can be assured that the wind turbine mast and the tower crane remain vertical, which makes installation easier.

[0425] The tower crane may also be used for other purposes than installation of a blade, e.g. used for exchanging a component from the nacelle of the wind turbine, e.g. for installation or replacing the gearbox or generator of the wind turbine.

[0426] The method for erecting the tower crane 1100 comprises mounting the annular crane base 1110 on the lower end of the wind turbine mast 1001. For example, the crane base is mounted on support brackets provided on the lower end of the wind turbine mast, Figures 15a-d show the steps of mounting the first base segment 1110a on the lower end of the wind turbine mast or foundation, e.g. monopile 1001. Figure 15e shows an enlarged view of the step shown in Figure 15c.

[0427] Figure 15a shows the first base segment 1110a being lifted by a crane, not shown, wherein the slewable jib unit 1103, the crane tower lifting unit 1108, and the horizontal stabilisers 1140 have been already installed on the first base segment 1110a. The wind turbine mast or foundation 1001 has two trunnions 1150 at two opposing points.

[0428] Figure 15b shows the first base segment 1110a being brought into engagement with the wind turbine mast or foundation 1001. The engagement pad 1154 is in engagement with the wind turbine mast or foundation, while the guiding structure of the support members 1152 helps guide the trunnions 1150 into the respective receiving space of the support members The actuating cylinder 1161 is extended such that first angle b1 between the first rod 1158 and the second rod 1159 is smaller than 180 degrees.

[0429] Figure 15c shows the first base segment 1110a being moved vertically downward such that the trunnions 1150 are received in the receiving space of the support members 1152 such that the first base segment 1110a is supported by both the support structure 1151 and the anti-tilt support mechanism 1153. As shown the first base segment 1110a is not fully horizontal with respect to the wind turbine mast 1001.

[0430] Figure 15d shows the first base segment 1110a with the actuating cylinder 1161 of the support mechanism 1153 in the retracted state, such that the first base segment 1110 is horizontal with respect to the wind turbine mast 1001. The first angle b1 between the first rod 1158 and the second angle 1159 being larger than 180 degrees. The second base segment 1110b can now be connected to the first base segment 1110a.

[0431] For example, as shown, the mounting step not only places the crane base on the lower end of the mast or on the foundation 1001, but also the crane tower lifting unit, the tower segments, the segment transfer trolley, and the winch trolley with winches thereon. Also, preferably all in one unit, the jib unit may be transferred in the mounting step as a whole with these components of the crane.

[0432] The method further comprises a crane tower assembly phase, in which the crane tower 1101 is erected by stacking tower segments 1102 one-by-one from below under the slewable lifting jib unit 1103 to form the crane tower, in which crane tower assembly phase the crane tower lifting unit 1108 lifts the already assembled part of the crane tower

[0433] In a preferred embodiment of the method, the lifting jib 1105 and the counter jib 1106 are in the substantially vertical upward orientation during the crane tower assembly phase. This position is achieved primarily by the luffing cylinders.

[0434] In an embodiment, during the crane tower assembly phase the tower segments 1110 are engaged and moved from a storage position SP on the crane base 1110 to an installation position IP at the crane tower lifting unit 1108 by the tower segment transfer trolley 1111. In the installation position IP the tower segment 1102 is below and aligned with the lifted already assembled part of the crane tower 1101.

[0435] In an embodiment, the vessel 1020 is equipped with two cranes 1021, wherein the cranes are used in tandem to transfer the tower crane 1100 to the offshore wind turbine 1000.

[0436] The invention further relates to a method for operating a tower crane 1100 described herein, wherein the winch trolley 1113 described herein travels along the winch trolley track when the slewable jib unit 1103 slews, such that the winch trolley remains aligned with the outer end of the counter jib 1106.

[0437] The invention further relates to a method for installing a wind turbine blade 1004 on a horizontal axis rotational hub 1003 of an offshore wind turbine, wherein the method comprises lifting a blade to be installed to a blade installation position blp, and attaching the blade that has been lifted to the blade installation position to the horizontal axis rotational hub of the offshore wind turbine, wherein the wind turbine blade is suspended from the hoisting cable by a blade lifting tool, wherein the method comprises:

[0438] - bringing the blade manipulator trolley 1132 in a lower position thereof,

[0439] - bringing the blade lifting tool 1125 in engagement with the blade manipulator 1134 in the lower position thereof, e.g. by operating the winch(es) 1138 to pull the tool 1125 into such engagement,

[0440] - lifting the wind turbine blade 1004 to the blade installation position blp by operating the hoisting winch 1121 and simultaneously moving the blade manipulator trolley 1132 along the blade manipulator trolley track 1130, e.g. by the trolley drive, such that the blade manipulator and the blade lifting tool stay in constant engagement with each other. The blade manipulator 1134 and the blade lifting tool 1125 are brought in engagement with each other by operating the one or more manipulator winches 1138. The manipulator cables 1139 are reeled in by operating the manipulator winches, such that the blade lifting tool 1125 supporting the blade 1004 is pulled towards and brought in engagement with the blade manipulator 1134.

[0441] In embodiments, the actuating assembly and associated positioning system of the manipulator are operated to position the root end of the blade when attaching the blade to the rotational hub,

[0442] The vessel 1020 used for transportation of the tower crane 1100 may also be used for transportation of the blades 1004 to be installed on the offshore wind turbine. A crane 1021 is used for transfer of the blade to be installed from the vessel, e.g. from a blade rack mounted thereon, to a lower receiving position where the tool 1125 is brought into engagement with the blade manipulator.

[0443] The hoist system comprising 1121 of the tower crane 1100 comprising the hoisting cable 1120, hoisting winch 1121 , and blade lifting tool 1125 is used to pick-up the blade directly from a vessel 1020. Herein the blade is held on the vessel by means of a motion compensated platform 1022, e.g. a heave compensated platform, so that the blade can be held in a motion compensated mode before the hoist system is engaged with the blade for its pick-up, e.g. using the spreader structure. Possibly, the blade is then first lifted a bit to clear the vessel, or platform thereof, and only then brought into engagement with the blade manipulator, e.g. by reeling in the blade manipulator cables. So the blade is then first attached to the hoist system and then to the manipulator assembly. There after the blade is lifted to a blade installation position.

[0444] Fig. 12a shows an embodiment of the horizontal stabiliser 1140.

[0445] The horizontal stabiliser 1140 comprises a horizontal stabiliser trolley 1141 and a base structure 1142.

[0446] The horizontal stabiliser trolley 1141 is engaged on the guide rails and configured to move along the height of the tower crane 3, 1101 , here shown as a latticed box structure. As shown, the guide rails are integrated with the chords of the tower crane 3, 1101. The base structure 1142 is arranged on the horizontal stabiliser trolley 1141 and extends along the width of the stabiliser trolley 1141. The horizontal stabiliser 1140 comprises two arms 1143 which extend from the base structure 1142 and wherein each arm 1143 is further provided with and a telescopic jaw 1144.

[0447] The arms 1143 are pivotably connected to the base structure 1142 in the proximity of the centre point of said structure and configured to pivot about an arm pivot axis ai.

[0448] The telescopic jaws 1144 each comprise a base portion 1144a and a telescopic portion 1144b, wherein the telescopic portion 1144a is configured to extend relative to the base portion 1144b. The base portion 1144a is at an inner end thereof pivotably connected to the outer end of the respective arm 1143 at a pivot point P and around a jaw pivot axis a2. The jaw pivot axes a2 being parallel to the arm pivot axes ai.

[0449] Each arm 1143 is provided with an arm cylinder 1145. The arm cylinders 1145 are pivotably connected to the outer end of the base structure 1142, at one end thereof and at the other end thereof pivotably connected to the pivot point P. The arm cylinders 1145 are configured to pivot the arms 1143 around the arm pivot axis ai with respect to the base structure 1142.

[0450] Each telescopic jaw 1144 is provided with a jaw cylinder 1146, which is at one end thereof pivotably connected to the respective arm 1143 and at the other end pivotably connected to the inner end of the base portion of the jaw 1144a. The jaw cylinders 1146 being configured to pivot the telescopic jaw 1144 around the jaw pivot axis a2 with respect to the respective arm 1143.

[0451] The telescopic jaws 1144 are provided with telescopic cylinders, not shown, which are configured to extend the telescopic portion 1144b with respect to the base portion of the telescopic jaws 1144a.

[0452] The horizontal stabiliser is further provided with four engagement pad assemblies 1147, which are configured to engage the wind turbine mast 210, 1001.

[0453] The outer ends of the telescopic portions 1144b are provided with an engagement pad assembly 1147, wherein the engagement pad assembly is pivotably connected to the outer end of the telescopic portions around an engagement pad pivot axis as. Two engagement pad assemblies 1147 are connected at the pivot point P and around a respective engagement pad pivot axis as, such that the jaw pivot axes a2 and the engagement pad pivot axes as coincide.

[0454] The engagement pad assemblies 1147 comprise a vertical structure which is pivotably connected to either the pivot point or the outer end of the telescopic portion. Two horizontal rows, each comprising four engagement pads, are provided at an upper end of the vertical structure, and two horizontal rows are provided at the lower end of the vertical structure.

[0455] The base structure 1142 is pivotably connected to the horizontal stabiliser trolley 1141 around a horizontal pivot axis a4. This allows the horizontal stabiliser to be pivoted from a substantial horizontal engagement position, shown in figure 12a, wherein the engagement pads can engage the wind turbine mast, and a substantial vertical storage position, shown in figure 12b.

[0456] As shown in figures 12c-e, the telescopic jaws 1144 in combination with the pivotably connected arms 1143, jaws 1144, cylinders 1145, 1146, and engagement pads 1147, allows the horizontal stabiliser to engage wind turbine masts 210, 1001 of different diameters.

[0457] Figures 17a and 17b schematically show a jack-up vessel 2100 which is positioned nearby a wind turbine mast 2010 provided with a nacelle 2011 . A self-climbing crane 2000 is installed on the hull to extend upward from the deck 2101 of the vessel 2100. The self-climbing crane

[0458] 2000 comprises of tower segments 2001 and a slewable jib unit 2002 with a lifting jib 2003 and a counter jib 2004.

[0459] The crane 2000 is transported on the jack-up vessel 2100 while the crane 2000 is not yet assembled, and the tower segments 2001 may be stored in the vertical orientation thereof on the deck of the vessel 2101. When the jack-up vessel 2100 is positioned correctly near the offshore wind turbine, the self-climbing crane 2000 is erected by stacking the tower segments

[0460] 2001 from below using a crane tower lifting unit 2005, as can be seen in Figure 17a.

[0461] As shown in Figure 17b, the crane 2000 is then used to install a wind turbine blade 2012 to the hub of the nacelle 2011 . The crane 2000 is erected at some distance from the wind turbine mast 2010, which allows the crane to lift the wind turbine blade 2012 at the centre of gravity while using a lifting jib 2003 with a limited length. In figure 17c it is shown that the jack-up vessel 2100 is provided with a movable cantilever on which the crane 2000 is arranged. The cantilever 2120 can be moved relative to the hull so as to allow the crane 200 to be close or at some distance from the wind turbine mast, whilst the legs of the vessel are favourably spaced from the foundation, here monopile, of the wind turbine. This is advantageous, e.g., in view of any scour protection around the foot of the bottom fixed foundation which is then not disturbed by the leg(s) of the vessel.

Claims

C L A I M S1 . Method for erecting a self-climbing tower crane on a support, e.g. a support adjacent or on a lower end of a wind turbine mast, e.g. on a foundation, e.g. on a monopile or on a floating foundation, wherein the tower crane comprises:- a crane base configured to be placed on the support,- tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base,- a crane tower lifting unit which is configured to be mounted on the crane base, wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below,- a slewable jib unit, wherein the slewable jib unit comprises:• a crane housing having a base end and a top end, wherein the base end is configured to be mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;• a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;• a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and wherein the counter jib, e.g. at the outer end thereof, is provided with a counter ballast or is mechanically loaded by a counter cable connected to a counter winch, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; wherein, optionally, the first and second luffing assemblies are independently operable from each other, and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit, wherein the method comprises a crane tower assembly phase, in which the crane tower is erected by stacking tower segments one-by-one from below under the slewable lifting jib unit to form the crane tower, in which crane tower assembly phase the crane tower lifting unit lifts the already assembled part of the crane tower, wherein - during the lifting of the assembledpart of the crane - the lifting jib and the counter jib are in the substantially vertical upward orientation.

2. Method according to claim 1 , wherein the crane tower lifting unit comprises a vertical lifting column and a lifting tool which is movable along the vertical lifting column, wherein - during the crane tower assembly phase - the lifting tool engages a tower segment, e.g. at the lower end thereof, and lifts an already assembled part of the crane tower including said tower segment to such a height that a further tower segment can be placed under the crane tower, and wherein the crane tower is subsequently connected to the further tower segment, e.g. the already assembled part of the crane tower being lowered and connected to the further tower segment.

3. Method according to claim 1 or 2, wherein the crane base is configured to store the tower segments thereon at respective storage positions (SP), and wherein the crane base is provided with a tower segment transfer trolley, wherein the tower segment transfer trolley is configured to engage a tower segment at the respective storage position (SP) and to move the tower segment to an installation position (IP) where the tower segment is positioned underneath and aligned with the lifted and already assembled part of the crane tower.

4. Method according to any one or more of claims 1 - 3, wherein the crane tower comprises lower and upper tower segments, and wherein each lower tower segment comprises an inner lower tower segment and an outer lower tower segment, the inner lower tower segment having a longitudinal axis, wherein the outer lower tower segment telescopically envelopes the inner lower tower segment so as to be movable along the longitudinal axis of the inner lower tower segment between a retracted and an extended position, wherein - during the crane tower assembly phase - the method further comprises the following steps:- connecting the upper portion of the outer lower tower segment to the lifted crane tower, wherein the outer lower tower segment is in the retracted position;- engaging the lifting tool to the lower portion of the outer lower tower segment;- moving the outer lower tower segment from the retracted position to the extended position;- locking the outer lower tower segment relative to the inner lower tower segment.

5. Method according to any one or more of the claims 1 - 4, wherein the crane tower is provided with one or more stabiliser devices which are configured to connect the crane towerto a wind turbine mast, wherein the one or more stabiliser devices are each configured to clamp onto the wind turbine mast, wherein each stabiliser device has a crane tower portion and a clamping portion, wherein - during the crane tower assembly phase - the one or more stabiliser devices are installed on the crane tower and engage the wind turbine mast.

6. Method according to claim 5, wherein multiple of the tower segments, e.g. all of the tower segments, are each provided with at least one guide rail extending along the height of the tower segment such that the guide rails of the interconnected tower segments form a substantially continuous guide rail, wherein the one or more stabiliser devices are mounted on the guide rail, e.g. to move along the height of the crane tower, preferably - before being moved along the height of the crane tower - the stabiliser device disengages the wind turbine mast and reengages the wind turbine mast when the stabiliser device is in the correct position.

7. Method according to claim 6, wherein the crane is provided with one or more stabiliser hoist devices, e.g. one or more winches, which one or more stabiliser hoist devices are arranged on the crane tower or on the jib unit, e.g. on the base end of the crane housing, and wherein the one or more stabiliser hoist devices hoist the one or more stabiliser devices along the crane tower, e.g. while the one or more stabiliser devices are engaged with the guide rail.

8. Method according to any one or more of claims 1 - 7, wherein the tower crane is erected along a wind turbine, e.g. an offshore wind turbine, the wind turbine comprising a wind turbine mast mounted on a foundation, e.g. mounted on an offshore foundation, e.g. on a monopile foundation or on a floating foundation, wherein the crane base is configured to be mounted on or near a lower end of the wind turbine mast, e.g. on support brackets provided on a lower end of the wind turbine mast or on the foundation, wherein, preferably, the crane base is annular and encircles the wind turbine mast or a part of the foundation, wherein the crane tower lifting unit is mounted on the crane base, and wherein the slewable jib unit is placed in an installation position at or in proximity of the crane tower lifting unit, wherein the tower segments are arranged in their vertical orientation, e.g. side by side, on the crane base, e.g. in an array extending over an arc-segment of the annular crane base, e.g. the crane base comprises a tower segment transfer device, e.g. a tower segment transfer trolley which is configured and operated to move the tower segments in succession from theirrespective storage position to an installation position where the tower segment is assembled with the crane tower, wherein the method further comprises the following steps:- transporting the tower crane to the wind turbine, e.g. using two cranes on a crane vessel;- mounting the crane base on the lower end of the wind turbine mast or on the foundation, preferably the crane base being mounted on support brackets provided on the lower end of the wind turbine mast or on the foundation.

9. Method according to claim 8, wherein - during the crane tower assembly phase - the tower segments are engaged and moved from a storage position on the crane base to an installation position at the crane tower lifting unit by a tower segment transfer trolley which is configured and operated to move the tower segments in succession from their respective storage position to an installation position where the tower segment is assembled with the crane tower.

10. Method according to claim 8 or 9, wherein the crane base is annular and comprises two base segments, wherein first a first base segment is mounted, e.g. on a support bracket, at the lower end of the wind turbine mast, and wherein subsequently a second base segment is mounted, e.g. on another support bracket, and connected to the first base segment, wherein, optionally, each base segment is provided with a transfer trolley track, wherein - when the two base segments are connected to each other - the transfer trolley tracks form a continuous transfer trolley track along which the tower segment transfer trolley moves.

11. Method according to any one or more of claims 8 - 10, wherein the tower crane is provided with a winch trolley, e.g. wherein the crane base is provided with the winch trolley, wherein the hoisting winch and the counter cable winch are mounted on the winch trolley, wherein the winch trolley is configured to move in a horizontal plane relative to the crane base so as to follow slew motion of the jib unit, wherein, preferably, the crane base is provided with a winch trolley track, preferably a circular winch trolley track, e.g. wherein each base segment is provided with a winch trolley track, wherein - when the two base segments are connected to each other - the winch trolley tracks form a continuous winch trolley track along which the winch trolley can move along.

12. Method for simultaneously erecting a tower crane on a support according to the method of the any one or more of claims 1 - 11 and constructing a wind turbine mast at a hoisting site, wherein the wind turbine mast comprises multiple wind turbine mast segmentswhich are configured to be stacked onto one another from above, wherein during the crane tower assembly phase according to any of the preceding claims - once the slewable lifting unit is sufficiently high - the slewable lifting unit is used to lift a wind turbine mast segment onto the top of the already installed wind turbine mast segments.

13. A self-climbing tower crane which is configured to be arranged on a support, e.g. a support at or near a foot of a wind turbine mast, e.g. on a foundation, e.g. on an offshore foundation, e.g. on a monopile or on a floating foundation, wherein the tower crane comprises:- a crane base configured to be placed on the support,- tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base,- a crane tower lifting unit which is configured to be mounted on the crane base, and wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit stepwise lifts the crane tower from below,- a slewable jib unit, wherein the slewable jib unit comprises:• a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;• a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;• a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and wherein the counter jib, e.g. at the outer end thereof, is provided with a counter ballast, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; wherein, optionally, the first and second luffing assemblies are independently operable from each other, and wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit, preferably wherein the lifting jiband the counter jib are configured to both be in the substantially vertical orientation during the process of stacking of the tower segments.

14. Crane according to claim 13, wherein the crane tower comprises an upper section to be composed of a series of multiple upper tower segments and a lower section to be composed of a series of multiple lower tower segments, the lower section being configured to support the upper section thereon, wherein both the upper and lower tower segments are embodied as tubular girder type tower segments, and wherein the upper and lower end portions of the upper and lower tower segments are provided with connectors to rigidly interconnect the tower segments.

15. Crane according to claim 13 or 14, wherein the crane tower further comprises one or more upper stabiliser devices and one or more lower stabiliser devices, each configured to horizontally connect the crane tower to an external tall structure, e.g. to a wind turbine mast.

16. Crane according to any one or more of claims 13 - 15, wherein the first and second luffing assemblies each comprise: o a luffing sheave assembly which is arranged at or near the top end of the crane housing; o a luffing winch and associated luffing cable, preferably the luffing winch being arranged inside of the upper crane housing section, wherein the luffing cable of the first luffing assembly is guided via the respective luffing sheave assembly to the lifting jib, e.g. the outer end thereof, to enable pivoting of the lifting jib about the lifting jib pivot axis, and wherein the luffing cable of the second luffing assembly is guided via the respective luffing sheave assembly to the counter jib, to enable pivoting of the counter jib about the counter jib pivot axis.

17. Crane according to any one or more of claims 13 - 16, wherein a hoisting winch is arranged at the crane base of the tower crane, e.g. on a winch trolley, wherein the hoisting cable extends from the hoisting winch along a side of the crane tower to the crane housing, and wherein the hoisting cable extends from the crane housing to a hoisting sheave assembly arranged at the outer end of the lifting jib, and wherein the hoisting cable extends between the hoisting sheave assembly to a load connector, preferably in a multi-fall arrangement.

18. Crane according to any one or more of claims 13 - 17, wherein the crane tower lifting unit comprises a vertical lifting column, wherein the vertical column comprises a base end and a top end, and wherein the crane tower lifting unit further comprises a lifting tool which isconfigured to engage a tower segment, e.g. at a lower end thereof, preferably at connector members of the tower segment, and a hoisting assembly, and wherein, optionally, the hoisting assembly of the crane tower lifting unit comprises one or more hoisting winches and associated hoisting cables, e.g. also a hoisting sheave assembly arranged at or near the top end of the vertical lifting column, wherein the hoisting cable is guided via the hoisting sheave assembly to the lifting tool.

19. Crane according to any one or more of claims 13 - 18, wherein the crane base is provided with a tower segment transfer trolley which is horizontally movable, e.g. along a track, between one or more storage positions for storage of tower segments and an installation position at the crane tower lifting unit, wherein, optionally, the tower segment transfer trolley is provided with mounting members on which a tower segment in vertical orientation can be mounted, wherein the transfer trolley is configured to move the tower segment from the storage position to the installation position at the crane tower lifting unit allowing the tower segment to be positioned underneath and aligned with a lifted already assembled part of the crane tower.

20. A self-climbing tower crane which is configured to be arranged on a support, e.g. on a support at lower end of a wind turbine mast or on a foundation, e.g. on an offshore foundation, e.g. a monopile or on a floating foundation, wherein the tower crane comprises:- a crane base, e.g. an annular crane base, configured to be mounted on the support, e.g. on support brackets,- tower segments which are configured to be stacked onto one another from below in order to erect a crane tower which is composed of the tower segments on the crane base,- a crane tower lifting unit which is mounted on the crane base, wherein the crane tower lifting unit is configured to perform lifting actions in the process of stacking of the tower segments, wherein the crane tower lifting unit is configured to stepwise lift the crane tower from below,- a slewable jib unit, wherein the slewable jib unit comprises:• a crane housing having a base end and a top end, wherein the base end is mounted on top of the crane tower, and wherein the crane housing is provided with a slew bearing;• a lifting jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a lifting jib pivot axis, and a first luffing assembly which is configured to pivot the lifting jib between a substantially horizontal orientation and a substantially upward vertical orientation;• optionally, a counter jib having an inner end and an outer end, wherein the inner end is pivotally mounted to the crane housing around a counter jib pivot axis, and whereinthe counter jib, e.g. at the outer end thereof, is mechanically loaded by a counter cable which is connected to a counter winch arranged on the crane base, and a second luffing assembly which is configured to pivot the counter jib between a substantially horizontal orientation and a substantially upward vertical orientation; wherein the tower crane is configured to - with the slewable jib unit connected to a tower segment - erect the tower crane by stacking the tower segments onto one another from below to lengthen the crane tower under the slewable jib unit.

21. Crane according to claim 20, wherein the counter cable extends from the counter winch to a counter jib sheave assembly provided on the counter jib, and from there, preferably in a multi-fall arrangement, via a crane housing sheave assembly mounted on the crane housing to a lifting jib sheave assembly on the lifting jib, optionally with a dead end of the counter cable near the counter winch.

22. Crane according to any one or more of claims 13 - 21 , preferably claim 20 or 21 , wherein the first and second luffing assemblies are embodied with a first luffing cylinder and a second luffing cylinder, e.g. hydraulic luffing cylinders, respectively, the first and second lifting cylinders being configured to pivot the lifting jib and the counter jib between the horizontal orientation and the substantially upward vertical orientation.

23. Crane according to any one or more of claims 13 - 22, wherein the crane base is configured to store the tower segments thereon arranged in their vertical orientation, e.g. side by side on the crane base, e.g. in an array extending over an arc-segment of an annular crane base, preferably wherein the crane base comprises a tower segments transfer device configured and operated to move the tower segments in succession from their respective storage position to the installation position at the crane tower lifting unit where the tower segment is assembled with an already assembled part of the crane tower.

24. Crane according to any one or more of claims 13 - 23, wherein the crane base is an annular crane base and comprises two base segments, wherein the two base segments are configured to be connected to each other, wherein, optionally, the first base segment comprises a support structure which is configured to engage, e.g. to be mounted to, one or more support brackets, e.g. two trunnions, arranged on the lower end of the wind turbine mast, and wherein the first base segment comprises a support mechanism which is configured to engage the wind turbine mast at a location vertically below the support brackets, to counteract rotation of the first base segment relative to the wind turbine mast.

25. Crane according to any one or more of claims 13 - 24, wherein the crane base is provided with a tower segment transfer trolley, wherein the tower segment transfer trolley is configured to engage and move a tower segment to an installation position at the crane tower lifting unit allowing the tower segment to be positioned underneath and aligned with a lifted already assembled part of the crane tower, wherein, optionally, the crane base is provided with a transfer trolley track, wherein the tower segment transfer trolley is configured to engage and move along the transfer trolley track, e.g. between the storage positions and the installation position, e.g. wherein each semi-circular segment of the crane base is provided with a transfer trolley track, wherein - when the two semi-circular segments are connected to each other - the transfer trolley tracks form a continuous transfer trolley track along which the tower segment transfer trolley can move along.

26. Crane according to any one or more of claims 13 - 25, wherein the crane base is provided with a winch trolley, wherein a hoisting winch and the counter cable winch are mounted on the winch trolley, wherein the winch trolley is configured to follow slew motion of the jib unit, preferably wherein the crane base is provided with a winch trolley track, preferably each base segment is provided with a winch trolley track, wherein - when the two semicircular segments are connected to each other - the winch trolley tracks form a substantially continuous winch trolley track along which the winch transfer trolley can move along.

27. Crane according to any one or more of claims 13 - 26, wherein tower segments are each provided with a blade manipulator trolley track which extends along the length of the tower segment, such that a continuous blade manipulator trolley track is formed along the length of the crane tower, wherein, optionally, the tower crane further comprises a blade manipulator assembly comprising: a blade manipulator trolley configured to engage the blade manipulator trolley track and being movable along the track in vertical direction, a blade manipulator trolley drive for moving the blade manipulator trolley along the blade manipulator trolley track, a blade manipulator which is configured to engage the blade lifting tool, wherein the blade manipulator is supported by the blade manipulator trolley and configured to provide controlled motion in one or more degrees of freedom of the blade lifting tool and the blade engaged thereby.

28. Crane according to claim 27, wherein the blade manipulator comprises: a lateral guide bracket which is connected to the blade manipulator trolley,an axial guide bracket which is mounted on and movable, in the lateral direction of the blade, along the lateral guide bracket, an engagement member configured to be engaged with the blade lifting tool wherein the engagement member is mounted on and movable, in the axial direction of the blade, along the axial guide member.

29. Crane according to claim 27 or 28, wherein the blade manipulator assembly comprises an actuating assembly and an associated positioning system configured and to be operated to position the root end of the blade when attaching the blade to the hub, e.g. the actuating assembly comprising a lateral and axial drive to move the axial guide in the lateral direction and to move the engagement member in the lateral direction respectively.

30. Crane according to any one or more of claims 27 - 29, wherein the blade manipulator assembly further comprises one or more, preferably three, manipulator winches and associated manipulator cable(s), wherein the manipulator winches are arranged on the blade manipulator, preferably on the engagement member, wherein the manipulator cables are configured to be extended between the manipulator winches and the blade lifting tool allowing to pull the blade lifting tool towards and into engagement with the blade manipulator.

31. Method for the installation of a wind turbine blade on a horizontal axis rotational hub of a wind turbine, e.g. on land or offshore, the wind turbine comprising a wind turbine mast and a nacelle with a horizontal axis rotational hub provided on the top end of the wind turbine mast, wherein use is made of a tower crane according to any one or more of claims 13 - 30.

32. Method according to claim 31 , wherein use is made of a tower crane according to any one or more of claims 27 - 30, wherein the method comprises lifting a blade to be installed to a blade installation position and attaching the blade that has been lifted to the blade installation position to the horizontal axis rotational hub of the wind turbine, wherein the wind turbine blade is suspended from the hoisting cable by a blade lifting tool, wherein the method comprises:- bringing the blade manipulator trolley in a lower position thereof,- bringing the blade lifting tool in engagement with the blade manipulator in the lower position thereof, e.g. using the one or more manipulator winches and associated manipulator cable(s),- lifting the wind turbine blade to the blade installation position by operating the hoisting winch and simultaneously moving the blade manipulator trolley along the blade manipulator trolley track, e.g. by the blade manipulator trolley drive, wherein the blade manipulator and the blade lifting tool stay in constant engagement with each other,wherein, optionally, the blade manipulator and the blade lifting tool are brought in engagement with each other by operating the one or more manipulator winches.

33. Method according to claim 32, wherein the hoist system of the tower crane comprising the hoisting cable, hoisting winch, and the blade lifting tool, is used to pick-up the blade directly from a vessel, e.g. dedicated blade supply vessel, wherein the blade is held on the vessel by means of a motion compensated platform, e.g. a heave compensated platform, so that the blade can be held in a motion compensated mode before the hoist system is engaged with the blade for its pick-up, e.g. using the blade lifting tool, wherein preferably, the blade is then first lifted to clear the vessel, or platform thereof, and only then brought into engagement with the blade manipulator, e.g. by reeling in the one or more blade manipulator cables.

34. A jack-up vessel provided with self-climbing tower crane according to any one or more of claims 13 - 30, wherein the crane base is mounted to the jack-up vessel, e.g. secured to or integrated with the hull or to a mobile cantilever of the jack-up vessel.

35. Method for the installation of a wind turbine blade on a horizontal axis rotational hub of a wind turbine, e.g. on land or offshore, the wind turbine comprising a wind turbine mast and a nacelle with a horizontal axis rotational hub provided on the top end of the wind turbine mast, wherein use is made of a tower crane, e.g. a tower crane according to claims 13 - 30, comprising a hoisting cable and a hoisting winch, wherein the tower crane comprises a blade manipulator trolley which is configured to move along the height of the tower crane between a lower position and a blade installation position, wherein the method comprises lifting a blade to be installed to the blade installation position and attaching the blade that has been lifted to the blade installation position to the horizontal axis rotational hub of the wind turbine, wherein the wind turbine blade is suspended from the hoisting cable by a blade lifting tool, wherein the method comprises:- bringing the blade manipulator trolley in the lower position thereof,- bringing the blade lifting tool in engagement with the blade manipulator in the lower position thereof, e.g. using the one or more manipulator winches and associated manipulator cable(s),- lifting the wind turbine blade to the blade installation position by operating the hoisting winch and simultaneously moving the blade manipulator trolley along the height of the tower crane,e.g. by the blade manipulator trolley drive, wherein the blade manipulator and the blade lifting tool stay in constant engagement with each other, wherein, optionally, the blade manipulator and the blade lifting tool are brought in engagement with each other by operating the one or more manipulator winches.

36. Method according to claim 35, wherein the hoist system of the tower crane comprising the hoisting cable, hoisting winch, and the blade lifting tool, is used to pick-up the blade directly from a vessel, e.g. dedicated blade supply vessel, wherein the blade is held on the vessel by means of a motion compensated platform, e.g. a heave compensated platform, so that the blade can be held in a motion compensated mode before the hoist system is engaged with the blade for its pick-up, e.g. using the blade lifting tool, wherein preferably, the blade is then first lifted to clear the vessel, or platform thereof, and only then brought into engagement with the blade manipulator, e.g. by reeling in the one or more blade manipulator cables.

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