Method of building an offshore windmill

Abstract

A method of building an offshore windmill includes, using a 3D-heave-compensated crane, placing on a windmill pedestal a lifting jack having a receiving region, and fixing the lifting jack to the windmill pedestal such that the lifting jack can be later removed, and such that a windmill column can be placed within the receiving region directly on the windmill pedestal. The windmill generator is installed using the 3D-heave-compensated crane. The windmill column is partially erected on the windmill pedestal using the 3D-heave-compensated crane and the lifting jack. Before the windmill is fully erected, windmill blades are placed on the windmill generator using the 3D-heave-compensated crane, and the erection of the windmill column on the windmill pedestal is completed using at least the lifting jack. Using the 3D-heave-compensated crane, the lifting jack is removed from the windmill pedestal.

Claims

1. Method of building an offshore windmill on a windmill pedestal that is located offshore, comprising: providing a floating vessel comprising a 3D-heave-compensated crane on a deck thereof; providing at least one offshore windmill assembly and a lifting jack, wherein the offshore windmill assembly comprises a windmill generator, a plurality of windmill blades and at least two windmill column parts for forming a windmill column at a later stage, wherein the lifting jack is configured for receiving the windmill column in a receiving region thereof; moving said floating vessel, the lifting jack and the at least one offshore windmill assembly in proximity of the windmill pedestal; placing the lifting jack directly on the windmill pedestal using the 3D-heave-compensated crane and fixing the lifting jack to the windmill pedestal such that it can be later removed, and wherein the lifting jack is fixed to the windmill pedestal such that the windmill column can be placed within the receiving region directly on the windmill pedestal; installing the windmill generator using the 3D-heave-compensated crane; partially erecting the windmill column on the windmill pedestal using the 3D-heave-compensated crane and the lifting jack; installing the windmill blades on the windmill generator using the 3D-heave-compensated crane at a stage where the windmill column has been partially erected; fully erecting the windmill column on the windmill pedestal using at least the lifting jack; removing the lifting jack from the windmill pedestal using the 3D-heave-compensated crane.

2. The method according to claim 1, wherein the method further comprises, before placing the lifting jack, preparing the windmill pedestal for receiving the lifting jack.

3. The method according to claim 1, wherein, in installing the windmill generator, the windmill generator is installed on the lifting jack.

4. The method according to claim 1, wherein, in partially erecting the windmill column, at least a first one of the at least two windmill column parts is installed on the windmill pedestal, and wherein, in fully erecting the windmill column, the remaining ones of the windmill column parts are installed using the lifting jack for creating room between the windmill pedestal and the remaining part of the windmill column, as well as using the 3D-heave-compensated crane for moving the respective windmill column parts from the floating vessel to the pedestal.

5. The method according to claim 1, wherein, in providing the floating vessel, the at least two windmill column parts that are provided on the floating vessel are in the form of a telescopic windmill column in its retracted state.

6. The method according to claim 5, wherein, in partially erecting the windmill column, the telescopic windmill column is installed in its retracted state on the windmill pedestal, and wherein, in fully erecting the windmill column, the lifting jack is used to extend the telescopic windmill column.

7. The method according to claim 1, wherein, in installing the windmill blades, the windmill blades are installed sequentially, wherein the windmill generator is used to manipulate a position of a windmill hub of the windmill generator such that the respective windmill blade can be mounted thereto.

8. The method according to claim 1, wherein, in providing the floating vessel, the floating vessel is provided with an enhanced lifting jack that further comprises a cradle that is configured for i) receiving respective windmill parts, for ii) bringing said parts from a lower end of the lifting jack to an upper end of lifting jack for iii) manipulating, i.e. rotating, said parts to a vertical position, and for iv) bringing said parts to said receiving region.

9. Method of building an offshore windmill on a windmill pedestal that is located offshore, comprising: placing a lifting jack having a receiving region on the windmill pedestal using a 3D-heave-compensated crane that is positioned on a floating vessel, and fixing the lifting jack to the windmill pedestal such that the lifting jack can be later removed, and such that a windmill column can be placed within the receiving region directly on the windmill pedestal; installing a windmill generator using the 3D-heave-compensated crane; partially erecting the windmill column on the windmill pedestal using the 3D-heave-compensated crane and the lifting jack; installing a plurality of windmill blades on the windmill generator using the 3D-heave-compensated crane at a stage where the windmill column has been partially, but not fully, erected; completing the erection of the windmill column on the windmill pedestal using at least the lifting jack; removing the lifting jack from the windmill pedestal using the 3D-heave-compensated crane.

10. The method according to claim 9, wherein the method further comprises, before placing the lifting jack, preparing the windmill pedestal for receiving the lifting jack.

11. The method according to claim 9, wherein, installing the windmill generator comprises installing the windmill generator on the lifting jack.

12. The method according to claim 9, wherein the windmill column comprises at least two windmill column parts, and wherein partially erecting the windmill column comprises installing at least a first one of the at least two windmill column parts on the windmill pedestal, and wherein completing the erection of the windmill column comprises installing the remaining ones of the windmill column parts using the jack for creating room between the windmill pedestal and the remaining part of the windmill column.

13. The method according to claim 9, wherein the windmill column comprises at least two windmill column parts, and wherein the at least two windmill column parts are in the form of a telescopic windmill column in its retracted state.

14. The method according to claim 13, wherein, in partially erecting the windmill column, the telescopic windmill column is installed in its retracted state on the windmill pedestal, and wherein, in completing the erection of the windmill column, the lifting jack is used to extend the telescopic windmill column.

15. The method according to claim 9, wherein, in installing the windmill blades, the windmill blades are installed sequentially, wherein the windmill generator is used to manipulate a position of a windmill hub of the windmill generator such that the respective windmill blade can be mounted thereto.

16. The method according to claim 9, wherein, the lifting jack comprises a cradle that is configured for i) receiving respective windmill parts, for ii) bringing said parts from a lower end of the lifting jack to an upper end of lifting jack, for iii) manipulating said windmill parts to a vertical position, and for iv) bringing said windmill parts to said receiving region.

Description

BRIEF INTRODUCTION OF THE DRAWINGS

(1) In the following is described examples of embodiments illustrated in the accompanying drawings, wherein:

(2) FIGS. 1 to 25 show different stages of an embodiment of the method of building an offshore windmill in accordance with this disclosure;

(3) FIG. 26a shows a top view of an embodiment of an advanced lifting jack in accordance with this disclosure, wherein the lifting jack is in an open position;

(4) FIG. 26b shows a top view of the lifting jack of FIG. 26a, wherein the lifting jack is in a closed position; and

(5) FIG. 27 shows a more detailed top view of the lifting jack of FIG. 26b, wherein the cradle is swung from an outer position to a centre position.

DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS

(6) Various illustrative embodiments of the present subject matter are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

(7) The present subject matter will now be described with reference to the attached figures. Various systems, structures and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.

(8) FIGS. 1 to 25 show different stages of an embodiment of the method of building an offshore windmill in accordance with this disclosure. FIG. 1 shows a first stage of this method. In this stage of the method there is provided a floating vessel 900, for instance an offshore crane ship. The vessel 900 has been provided with a 3D-heave compensated crane 910 on a deck 901 thereof. The 3D-heave compensated crane 910 is capable of lifting between 250 T or 400 T, for example. It is typically the windmill generator (nacelle), which is the heaviest part of the windmill assembly. A 6 MW nacelle/windmill generator (i.e. from RePower) typically weighs 316 T, so a 400 T crane will be able of installing most 6 MW nacelles and some 8 MW nacelles. A 5 MW nacelle (i.e. from Multibird) typically weighs 233 T, so a 250 T crane will be able to install most nacelle designs up to and including 5 MW.

(9) The vessel 900 is provided with offshore windmill parts, including a plurality of windmill column parts 110, a windmill generator 120, and a plurality of windmill blades 130. It must be noted that there may be a collection of other smaller parts, which is needed for mounting, fixing and installing the parts together, but all these details have been omitted in order not to obscure this disclosure. In FIG. 1 the vessel 900 has transported the windmill parts close to an offshore windmill pedestal 50 in a sea 1, so close that the pedestal is within reach of the crane 910. In addition to the windmill parts the vessel 900 is also provided with a lifting jack 90, which plays an important role in the method of this disclosure. In the embodiment shown of FIGS. 1 to 25, the pedestal 50 has been provided with a so-called pedestal adaptor 51, which serves to cooperate with the lifting jack 90 as will be explained later.

(10) FIG. 2 shows another stage of the method of building an offshore windmill. In this stage of the method, the lifting jack 90 is placed directly on the pedestal 50 using the crane 910. The load on the crane is typically in the order of 200 T (depending on the size of the windmill that is built) and is lifted and moved to the pedestal 50 in 3D-advanced heave compensation (3D-AHC) mode. The lifting jack 90 comprises fixing members 91, which facilitate placing and fixing the lifting jack 90 to the pedestal 50 via the pedestal adaptor 51. It must be noted that there exist also other ways of temporarily mounting a lifting jack 90 to an existing pedestal 50, which may render the pedestal adaptor 51 superfluous. In the figure there is two lifting legs 90-1, 90-2 visible, but in this embodiment there are three, as will be discussed with respect to FIGS. 26-27. The lifting jack 90 further comprises a cradle 95 mounted to one of its lifting legs 90-1. As will be further explained with reference to other figures this cradle 95 is used to lift windmill parts up to the upper end of the lifting jack 90, but also to manipulate the orientation of said parts to facilitate the building of the windmill. The cradle 95 is configured to slide along the respective lifting leg 90-1.

(11) FIG. 3 shows another stage of the method of building an offshore windmill. In this stage of the method, the windmill generator 120 is lifted and moved to the pedestal 50 using the crane 910 in 3D-AHC mode. The typical load on the crane 910 is 200-300 T, depending on the size of the windmill that is built. In this embodiment the windmill generator 120 is secured (i.e. bolted) to the top side of the lifting jack 90 as illustrated.

(12) FIG. 4 shows another stage of the method of building an offshore windmill. In this stage of the method a first one 110-1 of the three windmill column parts 110-1, 110-2, 110-3 is lifted with the crane 910. The typical load on the crane 910 is 70-100 T, depending on the size of the windmill that is built.

(13) FIG. 5 shows another stage of the method of building an offshore windmill. In this stage of the method, the lifting jack 90 is run up to its top position. In addition, the cradle 95 is moved towards a position in between the two extreme positions (maximum extension and minimum extension) as illustrated.

(14) The stages of FIGS. 4 and 5 can be easily exchanged, i.e. the lifting jack 90 can be run up before the first windmill column part 110-1 is lifted up by the crane 910.

(15) FIG. 6 shows another stage of the method of building an offshore windmill. In this stage of the method the first windmill column part 110-1 is moved to and placed on the cradle 95 (also referred to as catwalk) of the lifting jack 90 using the crane 910 in 3D-AHC mode.

(16) FIG. 7 shows another stage of the method of building an offshore windmill. In this stage of the method the first windmill column part 110-1 is clamped by the cradle 95 and rotated to a vertical position. More details about the cradle 95 to facilitate this are given with reference to FIGS. 26-27.

(17) FIG. 8 shows another stage of the method of building an offshore windmill. In this stage of the method the cradle 95 rotates around the respective lifting leg 90-1 to which it is mounted swinging the respective first windmill column part 110-1 to the centre region of the lifting jack 90 in between the pedestal 50 and the windmill generator 120. Furthermore, the windmill generator 120 has been landed on the first windmill column part 110-1 by letting the lifting jack 90 descend a little bit. Subsequently, the windmill generator 120 has been secured to the respective windmill tower part 110-1.

(18) FIG. 9 shows another stage of the method of building an offshore windmill. In this stage of the method, the first windmill column part 110-1 has been released and the cradle 95 has been swung outward to the outside region as illustrated. Furthermore, the lifting jack 90 has been further lowered until the first windmill column part 110-1 has landed on the pedestal 50. The first column part 110-1 has been temporarily secured to the pedestal 50, i.e. it will be detached from it at a later stage of the method. Finally, the lifting jack 90 has been released from the windmill generator 120 and lowered as illustrated.

(19) FIG. 10 shows another stage of the method of building an offshore windmill. In this stage of the method, a first one 130-1 of three windmill blades 130-1, 130-2, 130-3 is lifted using the crane 910 in 3D-AHC mode. The load on the crane in this stage is typically in the order of 15-35 T depending on the size of the windmill.

(20) FIG. 11 shows another stage of the method of building an offshore windmill. In this stage of the method, the first windmill blade 130-1 is moved to and placed on the cradle 95 using the crane 910 in 3D-AHC mode.

(21) FIG. 12 shows another stage of the method of building an offshore windmill. In this stage of the method, the first windmill blade 130-1 has been secured to (clamped by) the cradle 95 and rotated to a vertical position as illustrated. Subsequently the cradle 95 is moved up so that the first windmill blade 130-1 is touching the hub 121 of the windmill generator 120. The first windmill blade 130-1 is then mounted to the hub 121.

(22) FIG. 13 shows another stage of the method of building an offshore windmill. In this stage of the method, the cradle 95 is opened (releasing the first windmill blade 130-1) and rotated back to its horizontal position. Furthermore, a second one 130-2 of the three windmill blades is lifted using the crane 910 in 3D-AHC mode. The load on the crane in this stage is typically in the order of 15-35 T depending on the size of the windmill. In addition, the hub 121 of the windmill generator 120 is rotated 120 degrees.

(23) FIG. 14 shows another stage of the method of building an offshore windmill. In this stage of the method, the second windmill blade 130-2 is mounted to the hub 121 in a similar way as illustrated in FIGS. 11 to 13.

(24) FIG. 15 shows another stage of the method of building an offshore windmill. In this stage of the method, the third windmill blade 130-3 is mounted to the hub 121 in a similar way as illustrated in FIGS. 11 to 13.

(25) FIG. 16 shows another stage of the method of building an offshore windmill. In this stage of the method, the propeller is complete and the windmill generator 120 (also called Nacelle) is rotated 180 degrees around the pedestal axis 50a, such that the propeller of the windmill generator 120 is facing away from the vessel 900. This step creates the space for the further part of installation process, i.e. it substantially frees the cradle 95 of the lifting jack 90 for further lifting operations.

(26) FIG. 17 shows another stage of the method of building an offshore windmill. In this stage the second windmill column part 110-2 is lifted from the vessel 900 using the crane 910 in 3D-AHC mode. The typical load on the crane 910 is 70-100 T, depending on the size of the windmill that is built. The cradle 95 is opened (its clamping arm is released and moved away) and moved to a lower end of the lifting jack 90.

(27) FIG. 18 shows another stage of the method of building an offshore windmill. In this stage of the method, the first windmill column part 110-1 is fixed to the lifting jack 90 and subsequently detached from the pedestal 50. The lifting jack 90 has been subsequently lifted (extended) and the cradle 95 is moved to a location in between said two end positions, Finally, the second windmill column part 110-2 has been moved to and placed on the cradle 95 using the crane 910 in 3D-AHC mode, which is then locked and rotated 90 degrees to bring the second windmill column in a vertical position.

(28) FIG. 19 shows another stage of the method of building an offshore windmill. In this stage of the method, the second windmill column part 110-2 has been rotated with the cradle 95 towards the centre region of the lifting jack 90 in between the pedestal 50 and the first windmill column part 110-1.

(29) FIG. 20 shows another stage of the method of building an offshore windmill. In this stage of the method, the second windmill column part 110-2 is secured to the first windmill column part 110-1, and temporarily secured to the pedestal 50. Subsequently, the lifting jack 90 is retracted.

(30) FIG. 21 shows another stage of the method of building an offshore windmill. In this stage of the method, the lifting jack 90 has been coupled to a lower end of the second windmill column part 110-2, and the second windmill column part 110-2 has been subsequently detached from the pedestal 50. Finally, the lifting jack 90 is lifted to its maximum height, the third windmill column part 130-3 has been lifted, moved to and placed in the cradle 95 (using the crane 910 in 3D-AHC mode), locked, and rotated, similar to as discussed with reference to previous figures.

(31) FIG. 22 shows another stage of the method of building an offshore windmill. In this stage of the method, the third windmill column part 110-3 has been rotated with the cradle 95 towards the centre region of the lifting jack 90 in between the pedestal 50 and the second windmill column part 110-2. The third windmill column part 110-3 is secured to the second windmill column part 110-2, and to the pedestal 50.

(32) FIG. 23 shows another stage of the method of building an offshore windmill. In this stage of the method, the lifting jack 90 has been retracted, detached from the windmill, and is about to be removed (lifted up) by the crane 910 in 3D-AHC mode. The load on the crane 910 is typically in the order of 200 T (depending on the size of the windmill that is built).

(33) FIG. 24 shows another stage of the method of building an offshore windmill. In this stage of the method, the lifting jack 90 has been removed and placed on the vessel 900 by the crane 910. Subsequently, the lifting jack 90 is to be prepared for the next windmill.

(34) FIG. 25 shows another stage of the method of building an offshore windmill. In this stage of the method, the offshore windmill 100 has been completed.

(35) It has already been mentioned that in an advantageous embodiment of the method of this disclosure an enhanced lifting jack 90 is provided, having extra functionality besides the basic jacking function. This enhanced lifting jack 90 comprises a cradle 95 that is configured for i) receiving respective windmill parts, for ii) bringing said parts (in a horizontal position) from a lower end of the lifting jack to an upper end of lifting jack for iii) manipulating, i.e. rotating, said parts to a vertical position, where necessary, and for iv) bringing said parts to said receiving region. It has to be noted that the cradle 95 is advantageous, but not essential to this disclosure. Its function could be taken up by the crane, albeit that the crane then needs to be modified such that it can handle, hold and manipulate parts. Expressed differently, the crane needs to be turned into some sort of robot arm.

(36) FIG. 26a shows a top view of an embodiment of the advanced lifting jack 90 in accordance with this disclosure, wherein the lifting jack is in an open position. FIG. 26b shows a top view of the lifting jack of FIG. 26a, wherein the lifting jack is in a closed position. In these figures it is illustrated how the lifting jack 90 can be folded around an existing tubular structure if necessary. These figures also serve to illustrate how the earlier discussed fixing members 91 can be placed on the pedestal adaptor 51 as illustrated. The cradle 95 in this embodiment comprises effectively two receiving members 95-2 in order to receive the parts in a stable manner.

(37) FIG. 27 shows a more detailed top view of the lifting jack of FIG. 26b, wherein the cradle 95 is swung from an outer position to a centre position. A first feature that is illustrated in FIG. 27 are the locking members 96 that cooperate with the receiving members 95-1, 95-2 for holding/clamping respective parts. It must be noted that in FIG. 27 the cradle 95 in FIG. 27 has been rotated 90 degrees (for manipulating the respective part to a vertical position). Furthermore, the cradle 95 has been illustrated in four different swing positions, wherein it is visible that the cradle 95 may effectively swing in between said first 90-1 and third lifting leg 90-3 of the lifting jack 90 towards the centre region.

(38) The method as illustrated in FIGS. 1 to 26 is just one of the many possible embodiments. There are many variations on the embodiments possible, which has been extensively discussed above.

(39) In a further variation there is no cradle 95 on the lifting jack 90 as discussed with regards to FIGS. 26a, 26b and 27 earlier.

(40) For instance, it must be noted that the lifting jack 90 in FIG. 2 may be provided after provision of the first windmill column part 110-1. As illustrated in FIGS. 26a and 26b the lifting jack may be simply folded around the windmill column part and land on the pedestal adaptor 51 with its fixing members.

(41) Furthermore, the windmill generator 120 in FIG. 3 may also be placed later, i.e. after provision of the first windmill column part 110-1. In that case it may be directly mounted on the first windmill column part 110-1 instead of on the lifting jack 90. Alternatively, the windmill generator 120 in FIG. 3 may be placed on an already lifted (extended) lifting jack 90, even if no windmill column part 110-1 is placed underneath.

(42) In addition, the windmill column parts 110-1 . . . 110-3 may be partially replaced by (a) telescopic windmill column (part(s). The lifting jack 90 may be conveniently used to sequentially extend the telescopic column parts.

(43) Alternatively, the windmill blades 130-1 . . . 130 . . . 3 in FIGS. 10 to 16 may be installed after installation of two or more windmill column parts 110-1 . . 110-3. On one side this means that the crane may need to reach higher or be larger, while on the other side this allows for the installation of larger windmill blades.

(44) The particular embodiments disclosed above are illustrative only, and they may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the method steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope of this disclosure. Accordingly, the protection sought herein is as set forth in the claims below.

(45) It should be noted that the above-mentioned embodiments illustrate rather than limit this disclosure, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb comprise and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article a or an preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware.