Patent Description:
Crane vessels of this kind are used for building offshore wind turbines, wherein turbine components, such as a tower, a nacelle with a hub, and the blades are hoisted high above the waterline. The known crane vessels, as, for example, described in <CIT>, have a crane that comprises a slewing crane base and a very long boom that is rotatable connected with the crane base at the boom heel. This very long boom is raised and lowered by means of a luffing hoist tackle above the boom that is hauled in or paid out by a winch.

<CIT> and <CIT> disclose a crane vessel comprising a hull with a deck, and a crane on the hull for hoisting a load outside the deck. <CIT> further discloses that the crane comprises a slewing crane base, an elongated boom that is rotatable around a horizontal rotation axis with respect to the crane base, a single pendant between the boom and the crane base, a boom spacer between the boom and the crane base, and a boom luffing installation for driving the rotation of the boom around the horizontal rotation axis between a lowered transport position and a raised operational position, wherein the crane base comprises a slew platform and a base frame above the slew platform that forms a first suspension of the crane base for the boom, wherein the boom comprises a distal boom section with a boom tip and a proximal boom section, wherein the pendant has a first end and an opposite second end that is connected with the distal boom section, wherein the boom spacer has a first end that is rotatable connected with the first suspension for rotation around the horizontal rotation axis, and an opposite second end that is spaced apart from the first end and that is connected with the boom to keep the boom spaced apart from the horizontal rotation axis.

Known large offshore wind turbines typically have power of <NUM> Megawatt and require a lifting height for its components above the waterline of <NUM> meters. This lifting height is reached with the known cranes by using the very long boom that projects from the hull in the lowered transport position. Offshore wind turbines are continuously scaled up, wherein a power of <NUM> Megawatt is envisaged in the near future, and thereby significant higher lifting heights for the turbine components.

Using longer booms of the known crane for reaching higher lifting heights has disadvantages. A longer boom projects for example further from the hull what requires a heavy boomrest and cause sailing limitations. The cables in the luffing tackle are continuously wounded around between the slewing crane base and the tip of the boom and extend parallel to each other, so that in case of a lateral deflection of the boom tip, no resistance or sideward counter force against that is created in the luffing tackle. So when the boom tip is loaded by a side force due to a slight swing of the load or any other effect then the boom has to carry these loads. For such crane the global buckling or Euler column buckling effective length factor is high, whereby especially for a very long boom these effects require a lot of heavy weight for strengthening the boom, reducing the efficiency of these booms.

It is an object of the present invention to provide a crane vessel of the kind as described, having a crane that can meet future lifting heights without causing significant limitations as described before.

The invention provides a jack-up crane vessel or semi-submersible crane vessel comprising a hull with a deck, and a crane on the hull for hoisting a load outside the deck, wherein the crane comprises a slewing crane base that is rotatable with respect to the hull around a vertical rotation axis, an elongated boom that is rotatable around a horizontal rotation axis with respect to the crane base, at least two pendants between the boom and the crane base, a boom spacer between the boom and the crane base, and a boom luffing installation for driving the rotation of the boom around the horizontal rotation axis between a lowered transport position and a raised operational position, wherein the crane base comprises a slew platform and a base frame above the slew platform that forms a first suspension of the crane base for the boom, wherein the boom comprises a distal boom section with a boom tip and a proximal boom section with a boom heel, wherein the pendants have a first end that is connected with the first suspension and an opposite second end that is connected with the distal boom section, wherein the pendants mutually converge toward the distal boom section, wherein the boom spacer has a first end that is rotatable connected with the first suspension for rotation around the horizontal rotation axis, and an opposite second end that is spaced apart from the first end and that is connected with the boom heel to keep the boom spaced apart from the horizontal rotation axis, and wherein in the direction of the vertical rotation axis the first suspension extends at least in the lowered transport position of the boom above the boom heel of the boom.

The vessel according to the invention has a crane that comprises a slewing crane base with a first suspension, and a boom that is rotatable connected with the crane base via a boom spacer between the first suspension and the boom heel. The boom spacer guides the lift of the entire boom in the vertical direction when it is luffed to its operational position, which contributes to the effective height of the boom tip. The pendants converge from the first suspension toward the boom tip to form a triangle configuration in which the pendants are loaded under pure pulling forces. Any side forces created by a slight swinging of the load or any other effect in a sideward direction are taken by de pendants and transferred to the first suspension. This prevents the boom from bending, which improves the efficiency of the boom. The boom and the boom spacer form together with that triangle configuration a form stable tetrahedron configuration.

In an embodiment the boom spacer keeps the boom heel spaced apart from the horizontal rotation axis over a fixed distance to ensure the same tetrahedron configuration in both the lowered position and the raised position of the boom.

In an embodiment the first suspension extends in the raised position of the boom in the direction of the vertical rotation axis at about the same height as the boom heel of the boom.

In an embodiment extends in the raised position of the boom, the boom heel with respect to the first suspension at the opposite side of the vertical rotation axis.

In an embodiment the horizontal rotation axis extends in a projection parallel to the horizontal rotation axis in a direction transverse to the elongated direction of the boom aside the boom, whereby the horizontal rotation axis is located far outside the central axis or the outer side of the boom.

Quantitatively expressed the boom spacer may have a length between the horizontal rotation axis and the boom heel that is <NUM>-<NUM>% of the length of the boom between the boom tip and the boom heel.

In an embodiment the boom spacer is connected under an angle with the proximal boom section to provide the distance with the horizontal rotation axis in an efficient manner.

In an embodiment thereof the angle is a fixed angle.

In an embodiment the angle is <NUM>-<NUM> degrees.

In an embodiment the pendants have the same fixed length between the first end and the second end in the lowered transport position and in the raised operational position of the boom. Herein it is to be understood that the pendants may be stretched elastically under the applied pulling forces, but tackles and sheaves are not necessary. In this manner the pendants can be loaded without being subjected to curvatures around sheaves, that form potential wear spots or even break spots.

In an embodiment the pendants comprise a cable or rope between the first end and the second end.

In an embodiment thereof the rope or cable is based on a synthetic fiber, which can handle high pulling forces with respect to their specific weight, provided that they are not guided or curved around sheaves for example.

In an embodiment the first ends of the pendants are rotatable connected with the first suspension to ensure that they are loaded under pure pulling forces only.

The mutual converging of the pendants towards the distal boom section can be ensured when the first ends of the pendants are connected with the first suspension at a mutual distance in the direction of the horizontal rotation axis that is larger than the largest width of the distal boom section in that direction.

The mutual converging of the pendants towards the distal boom section can alternatively be ensured when the first ends of the pendants are connected with the first suspension at a mutual distance in the direction of the horizontal rotation axis that is larger than the largest width of the boom in that direction.

The mutual converging of the pendants towards the distal boom section can alternatively be ensured when the first ends of the pendants are connected with the first suspension at a mutual distance in the direction of the horizontal rotation axis that is larger than the largest width of the slew platform in that direction.

In an embodiment the boom spacer comprises two spacers that extend spaced apart from each other to define a passage in between, wherein the vertical rotation axis extends through the passage. This passage can be used to accommodate a leg of a jack-up vessel, whereby the crane can be built on top of a jacking house for that leg without being hampered by that leg in the luffing of the boom.

In an embodiment the boom luffing installation comprises a linear drive between the crane base and the boom heel.

In an embodiment the crane base comprises a second suspension at the opposite side of the first suspension with respect to the vertical rotation axis, wherein the boom luffing installation comprises a hoisting assembly between the second suspension and the boom heel.

In an embodiment the base frame comprises two upward box girders having a bottom end that is mounted to the slew platform spaced apart from each other, and two cross box girders having a bottom end that is mounted to the slew platform spaced apart from each other, wherein the upward box girders and the cross box girders are connected with each other at their opposite upper end in pairs to form two triangular frame configurations or A-frame configurations on opposite sides of the vertical rotation axis, wherein the first suspension is located at the top of the triangular frame configurations or A-frame configurations.

In an embodiment the crane comprises hoisting sheaves at the boom tip, a multi sheave hoisting block and a load hoisting tackle with multiple cable windings between the sheaves for hoisting a load.

In an embodiment the distal boom section is a latticed distal boom section. The lattice construction can be made from steel tubes or from relatively lightweight carbon fiber tubes.

The invention will be elucidated on the basis of exemplary embodiments shown in the attached drawings, in which:.

<FIG> shows a self-elevating jack-up crane vessel <NUM> during sailing at sea <NUM>. In this embodiment the crane vessel <NUM> is self-propelled, but alternatively the crane vessel <NUM> is towed by tugs. The crane vessel <NUM> comprises in this embodiment a rectangular hull <NUM> having a bow <NUM>, a stern <NUM> a port side <NUM>, a starboard side <NUM> and a large deck <NUM>. The crane vessel <NUM> comprises a steering house <NUM>, and in this example four upright legs <NUM> that are guided through jacking houses <NUM> having an internal drive to lower and raise each of the legs <NUM> in direction A as known per se to raise the hull <NUM> above the sea <NUM>. During sailing all legs <NUM> are raised and extend with their top side high above the deck <NUM> and the bridge <NUM>.

The crane vessel <NUM> comprises a crane <NUM> according to a first embodiment of the invention above a crane foundation <NUM> on the hull <NUM>. In this example the crane foundation <NUM> coincides with one of the jacking houses <NUM>, in this example above the rear starboard side jacking house <NUM>. The crane vessel <NUM> with the crane <NUM> is designed to handle large wind turbine components, such as a tower <NUM>, a nacelle <NUM> with a hub <NUM>, and blades <NUM> to build an offshore wind turbine <NUM> at an offshore installation site. The wind turbine components may be shipped on the deck <NUM> to the installation site, but alternatively a feeder barge is used to ship the wind turbine components to the crane vessel <NUM>.

On the installation site the crane vessel <NUM> is jacked up by lowering the legs <NUM> in direction A. The wind turbine components are installed aside the deck <NUM> by means of the crane <NUM>. The offshore wind turbine <NUM> typically has a power of <NUM> Megawatt and require a lifting height above the waterline of <NUM> meters. Offshore wind turbines are continuously scaled up, wherein a power of <NUM> Megawatt is envisaged in the near future, and thereby a higher lifting height for the turbine components. The crane vessel <NUM> with the crane <NUM> can meet this increasing future demand.

The invention is not limited to a jack-up crane vessel as shown in the figures. A jack-up rig with the crane <NUM> is considered a crane vessel according to the invention. The crane <NUM> may alternatively be installed on a semi-submersible crane vessel for performing the same kind of offshore hoisting operations as described above.

The crane <NUM> is shown in more detail in <FIG> and <FIG>. The crane <NUM> comprises a steel slewing crane base <NUM> around the leg <NUM> that is rotatingly mounted to the crane foundation <NUM> for rotation of the entire crane <NUM> in direction B around its vertical rotation axis Z, which in this example corresponds with the central axis of the leg <NUM> that extends through the jacking house <NUM>. In <FIG> and <FIG> the leg <NUM> is removed for illustrative purposes only.

The crane base <NUM> comprises a slew platform <NUM> and a rigid base frame <NUM> on the slew platform <NUM>. The base frame <NUM> comprises a back structure having two upward back box girders <NUM> that are at their bottom end mounted to the back side of the slew platform <NUM> and that diverge upwardly away from each other and away from the vertical rotation axis Z. The upward back box girders <NUM> are at their top end connected with a transverse back box girder <NUM>. The base frame <NUM> furthermore comprises two cross box girders <NUM> that are at their bottom end mounted to the front side of the slew platform <NUM> when considered in the direction of a horizontal axis Y and that diverge upwardly away from each other and away from the vertical axis Z and toward the upward back box girders <NUM>. The cross box girders <NUM> and the transverse back box girder <NUM> together form a portal <NUM> of the base frame <NUM>. The cross box girders <NUM> are at their top end connected with the respective upward back box girder <NUM>, close to the transverse back box girder <NUM> to form rigid triangular frame configurations or A-frame configurations on both sides of the vertical axis Z. The portal <NUM> forms a back suspension or first suspension <NUM> of the crane base <NUM> at the upper back of the base frame <NUM>, near the transverse back box girder <NUM>.

The crane base <NUM> comprises an upward front box girder <NUM> that is at its bottom end mounted to the front side of the slew platform <NUM>. The upward front box girder <NUM> supports at its top end a transverse front box girder <NUM> that at its ends merges into two angled side box girders <NUM>. The side box girders <NUM> are at their opposite end connected with the meeting ends of the upward back box girders <NUM> and the cross box girders <NUM> to form a rigid front suspension or second suspension <NUM> of the crane base <NUM> at the transverse front box girder <NUM>.

The crane <NUM> comprises a boom <NUM> that extends in a projection parallel to the vertical axis Z in the direction of the horizontal axis Y. The boom <NUM> comprises in this example a single, straight elongated distal boom section <NUM> with a boom tip <NUM>. In this example the distal boom section <NUM> is a latticed distal boom section <NUM>. The lattice construction can be made from carbon fiber tubes, or from steel tubes. In this example, the distal boom section <NUM> merges via a boom splitter <NUM> into two straight, elongated proximal boom sections <NUM> that form a boom heel <NUM> at the bottom. In this example the proximal boom sections <NUM> are box girder proximal boom sections <NUM>. The proximal boom sections <NUM> have an elongated first free space <NUM> in between for passage of the upward front box girder <NUM> and encircling the leg <NUM> that extends vertically through the crane base <NUM>. In this example the boom splitter <NUM> is positioned to come between the two legs <NUM> at the starboard side of the crane vessel <NUM> when the boom <NUM> is in its lowered transport position. It is also possible to position the boom splitter <NUM> beyond both these legs <NUM> whereby both these legs <NUM> extends through the first free space <NUM>. When the crane <NUM> is non-leg encircling, the proximal boom section can be a single proximal boom section with the boom heel. In that case the front upward box girder <NUM> can comprise two sections aside each other with the boom in between.

The crane <NUM> comprises a steel boom spacer <NUM> that extends between the boom heel <NUM> and the crane base <NUM>. The boom spacer <NUM> comprises two straight, elongated spacers <NUM> that extend spaced apart from each other between the respective proximal boom sections <NUM> and the first suspension <NUM>. The spacers <NUM> are latticed spacers or box girder spacers. The spacers <NUM> each have a first end <NUM> that is connected with a transverse top box girder <NUM> that is rotatable connected with the first suspension <NUM> for rotation in direction D around a horizontal rotation axis X. Thereby the boom spacer <NUM> has two rotation points with the first suspension <NUM>, that are spaced apart from each other in the direction of the horizontal rotation axis X. The spacers <NUM> each have an opposite second end <NUM> that merge under an angle C into the bottom ends of the proximal boom sections <NUM>. In this example these are rigidly connected with each other, under a fixed angle C of about <NUM>-<NUM> degrees. The proximal boom sections <NUM> and the spacers <NUM> may alternatively be connected with each other by means of hinges with a horizontal rotation axis that extends parallel to the rotation axis X at the first suspension <NUM>. The spacers <NUM> have an elongated second free space <NUM> in between that forms a continuation of the first free space <NUM> for passage of the front upward box girder <NUM> and the leg <NUM> that extends vertically through the crane base <NUM>.

The crane <NUM> comprises two elongated pendants <NUM> that extend between the first suspension <NUM> and the boom tip <NUM>. The pendants <NUM> mutually converge toward the distal boom section <NUM> to form a substantial triangular configuration. The pendants <NUM> each comprise a cable or rope <NUM> that is in this example based on a synthetic fiber, for example an aramid or a high performance polyethylene (HPPE) (for example known under the name Dyneema®), or carbon. The pendants <NUM> comprise a first end <NUM> on the rope <NUM> that is rotatable connected with the first suspension <NUM> to rotate around a horizontal rotation axis that is parallel to, or coincides with the horizontal rotation axis X of the boom spacer <NUM>. The two first ends <NUM> are spaced apart from each other at the first suspension <NUM> over a distance G that is larger than the largest width of the distal boom section <NUM>, and preferably larger than the largest width of the entire boom <NUM>. The distance G is also larger than the largest width of the slew platform <NUM> in that direction. The first ends <NUM> of the ropes <NUM> are in the proximity of their respective nearest rotation point of the spacers <NUM> to prevent the generation of bending moments in the transverse back box girder <NUM>.

The pendants <NUM> comprise a second end <NUM> on the rope <NUM> that is connected with the boom tip <NUM>. The ropes <NUM> have a fixed material length between the first end <NUM> and second end <NUM> of the pendants <NUM>. The ropes <NUM> may under this fixed material length stretch elastically due to a pulling force action on it. The pendants <NUM> mutually converge toward the boom tip <NUM> forming a triangular configuration. Alternatively the pendants <NUM> mutually converge toward the boom tip <NUM> while crossing each other before the boom tip <NUM>, giving effectively the same triangular configuration. In the operative position the boom <NUM> is loaded under a pressure force in its elongated direction while the pendants <NUM> are loaded under pure pulling forces, such that any side forces created by a load motion in sideward direction E, for example by a slightly swinging hoisted load or by any other external factor, are taken by the pendants <NUM> and transferred to the first suspension <NUM> where the first ends are spaced apart from each other over the distance G, which is forms the base of the triangle configuration of the pendants <NUM>. This base is located high in the base frame <NUM> of the crane base <NUM>. The pendants <NUM> give the boom tip <NUM> sideward stability against lateral bending of the boom <NUM> to prevent lateral buckling of the boom <NUM>.

The boom <NUM>, the boom spacer <NUM>, the first suspension <NUM> and the pendants <NUM> converging toward the boom tip <NUM> together form a form stable tetrahedron configuration having a free space <NUM> between the notional ribs of the tetrahedron. In this example the pendants <NUM> have their second ends <NUM> close to each other on the boom tip <NUM>.

The crane <NUM> comprises multiple hoisting sheaves <NUM> at the boom tip <NUM>, a multi sheave hoisting block <NUM> and a load hoisting cable <NUM> with multiple windings there between for hoisting the load. The boom <NUM> has a length H between the boom tip <NUM> and the boom heel <NUM>, and the boom spacer <NUM> has a length K between the boom heel <NUM> and the rotation axis X. The length K of the boom spacer <NUM> is <NUM>-<NUM>% of the Length H of the boom <NUM>.

The crane <NUM> comprises a boom luffing installation <NUM> between the boom spacer <NUM> and the front suspension <NUM>. The boom luffing installation <NUM> comprises a hoisting assembly <NUM> between the front suspension <NUM> and the boom heel <NUM>. The boom <NUM> can by means of the boom luffing installation <NUM> be lifted and rotated around the horizontal rotation axis X between its lowered position as shown in <FIG>, wherein in this example it is supported by a boomrest <NUM> in front of the steering house <NUM>, and its operational raised position for hoisting as shown in <FIG>. When the boom <NUM> is luffed into the operational position, the entire boom <NUM>, that is including the boom heel <NUM>, is lifted vertically upwards by the boom spacer <NUM> while the tetrahedron configuration remains stable.

By lifting the entire boom <NUM> with respect to the first suspension <NUM> in a vertical direction, having the horizontal rotation axis X in vertical direction higher located than the crane base <NUM> and spaced apart from the boom <NUM>, the maximum lifting height of the crane <NUM> is extended when compared to a traditional boom that is at the boom heel directly rotatable connected with a crane base and raised by means of a luffing hoist tackle above the boom. In the operational position as shown in <FIG>, the first suspension <NUM>, in particular the horizontal rotation axis X of the boom <NUM>, extends at about the same vertical height as the boom heel <NUM>. That is, within <NUM> meters vertical height difference in the direction of the vertical rotation axis Z.

<FIG>, <FIG> and <FIG> show a crane <NUM> according to a second embodiment of the invention on the jack-up house <NUM> of the jack-up crane vessel <NUM>. The components of this crane <NUM> that correspond with the crane <NUM> according to the first embodiment are provided with the same reference numbers. Only the deviating components are discussed hereafter and are provided with reference numbers added with <NUM>.

The crane <NUM> comprises a single, straight, elongated boom <NUM> that extends in the projection parallel to the vertical axis Z in the direction of the horizontal axis Y. The boom <NUM> has the boom tip <NUM> at its distal end and a boom heel <NUM> at the bottom of the proximal end. In this example the boom <NUM> is a latticed boom <NUM>. The lattice construction can be made from steel tubes. Alternatively the boom <NUM> is a single column, made of steel or carbon fiber.

The crane comprises a steel boom spacer <NUM> that extends between the boom heel <NUM> and the crane base <NUM>. The boom spacer <NUM> comprises two spacers <NUM> that are at a first end <NUM> rotatable connected with the first suspension <NUM> for rotation in direction D around the horizontal rotation axis. The spacers <NUM> converge from the first suspension <NUM> to the boom heel <NUM> where they are rigidly connected with at their second end <NUM>. In this example the spacers <NUM> are rigidly connected with the boom heel <NUM>, under a fixed angle C of about <NUM>-<NUM> degrees. The boom heel <NUM> and the spacers <NUM> may alternatively be connected with each other by means of hinges with a horizontal rotation axis that extends parallel to the rotation axis X at the first suspension <NUM>. Under the fixed angle C, the boom heel <NUM> extends in the operational, raised position as shown in <FIG> even above the first suspension <NUM> in the vertical direction parallel to the rotation axis Z. In this embodiment the boom heel <NUM> does not pass the upward front box girder <NUM>. The boom heel <NUM> extends in both the lowered transport position and in the raised operational position in front of the front box girder <NUM> in the direction of the horizontal axis Y.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention, which solely defined by the appended claims.

Claim 1:
Jack-up crane vessel (<NUM>) or semi-submersible crane vessel comprising a hull (<NUM>) with a deck (<NUM>), and a crane (<NUM>) on the hull (<NUM>) for hoisting a load outside the deck (<NUM>), wherein the crane (<NUM>) comprises a slewing crane base (<NUM>) that is rotatable with respect to the hull (<NUM>) around a vertical rotation axis (Z), an elongated boom (<NUM>, <NUM>) that is rotatable around a horizontal rotation axis (X) with respect to the crane base (<NUM>), at least two pendants (<NUM>) between the boom (<NUM>, <NUM>) and the crane base (<NUM>), a boom spacer (<NUM>, <NUM>) between the boom (<NUM>, <NUM>) and the crane base (<NUM>), and a boom luffing installation (<NUM>) for driving the rotation of the boom (<NUM>, <NUM>) around the horizontal rotation axis (X) between a lowered transport position and a raised operational position, wherein the crane base (<NUM>) comprises a slew platform (<NUM>) and a base frame (<NUM>) above the slew platform (<NUM>) that forms a first suspension (<NUM>) of the crane base (<NUM>) for the boom (<NUM>, <NUM>), wherein the boom (<NUM>, <NUM>) comprises a distal boom section (<NUM>) with a boom tip (<NUM>) and a proximal boom section (<NUM>) with a boom heel (<NUM>, <NUM>), wherein the pendants (<NUM>) have a first end (<NUM>) that is connected with the first suspension (<NUM>) and an opposite second end (<NUM>) that is connected with the distal boom section (<NUM>), wherein the pendants (<NUM>) mutually converge toward the distal boom section (<NUM>), wherein the boom spacer (<NUM>, <NUM>) has a first end (<NUM>, <NUM>) that is rotatable connected with the first suspension (<NUM>) for rotation around the horizontal rotation axis (X), and an opposite second end (<NUM>, <NUM>) that is spaced apart from the first end (<NUM>, <NUM>) and that is connected with the boom heel (<NUM>, <NUM>) to keep the boom (<NUM>, <NUM>) spaced apart from the horizontal rotation axis (X), and wherein in the direction of the vertical rotation axis (Z) the first suspension (<NUM>) extends at least in the lowered transport position of the boom (<NUM>, <NUM>) above the boom heel (<NUM>, <NUM>) of the boom (<NUM>, <NUM>).