Abstract
A support assembly for an offshore installation is provided, which support assembly includes a transition piece for mounting onto an offshore foundation; a plurality of support shelves, wherein each support shelf extends radially outward from the transition piece; a platform to accommodate equipment of the offshore installation, which platform includes a mounting sleeve dimensioned to fit about the transition piece; and wherein the mounting sleeve includes a plurality of downwardly-extending portions, each dimensioned to fit between two adjacent support shelves; and a plurality of lateral cut-outs, each formed in a downwardly-extending portion and shaped to receive a support shelf. An offshore wind-powered water electrolysis plant including such a support assembly, and a method of installing such a support assembly is also provided.
Claims
1. A support assembly for an offshore installation, the support assembly comprising: a transition piece for mounting onto an offshore foundation; a plurality of support shelves, wherein each support shelf extends radially outward from the transition piece; and a platform to accommodate equipment of the offshore installation, the platform comprising a mounting sleeve dimensioned to fit about the transition piece; wherein the mounting sleeve comprises: a plurality of downwardly-extending portions, each dimensioned to fit between two adjacent support shelves; and a plurality of lateral cut-outs, each formed in a downwardly-extending portion and shaped to receive a support shelf.
2. The support assembly according to claim 1, wherein the plurality of support shelves and the plurality of lateral cut-outs are formed to allow a rotation of the platform through an angle of at most 10, or at most 5.
3. The support assembly according to claim 1, wherein the support shelf comprises an upwardly-facing contact surface to receive a downwardly-facing contact surface of the corresponding lateral cut-out.
4. The support assembly according to claim 3, wherein the support shelf further comprises a portion extending into an interior of the transition piece, further wherein the portion comprises at least 50%, or at least 70%, of a total support shelf.
5. The support assembly according to claim 1, wherein the platform comprises a circular aperture to accommodate a base of a wind turbine tower, and the mounting sleeve extends about the circular aperture.
6. The support assembly according to claim 1, wherein the mounting sleeve comprises a plurality of outwardly-extending horizontal flanges, and wherein sleeve portions extend between an upper horizontal flange and a lower horizontal flange.
7. The support assembly according to claim 1, comprising a low-friction interface between the mounting sleeve and the transition piece.
8. An offshore wind-powered water electrolysis plant comprising: a support assembly according to claim 1, wherein the transition piece of the support assembly is mounted on an offshore foundation; a wind turbine comprising a tower which is connected to the transition piece of the support assembly; and a water electrolysis plant mounted on the platform of the support assembly, and wherein the wind turbine is configured to provide power for the water electrolysis plant.
9. The offshore wind-powered water electrolysis plant according to claim 8, wherein the platform and the water electrolysis plant have a combined mass in the order of 800 metric tons.
10. The offshore wind-powered water electrolysis plant according to claim 8, wherein a lower diameter of the wind turbine tower is in the order of 8 meters.
11. A method of installing a support assembly according to claim 1, the method comprising: mounting the transition piece onto an offshore foundation previously erected at an installation site; transporting the platform to the installation site; lowering the platform onto the transition piece to position each downwardly-extending sleeve portion of the mounting sleeve between two adjacent support shelves of the transition piece; and turning the platform relative to the transition piece until each lateral cut-out of the mounting sleeve engages with the corresponding support shelf.
12. The method according to claim 11, comprising a preliminary step of assembling a platform by: providing a mounting sleeve dimensioned to fit about the transition piece; providing a platform floor; and connecting the platform floor to the mounting sleeve.
13. The method according to claim 11, comprising a preliminary step of populating the platform with a complete water electrolysis plant.
14. The method according to claim 11, wherein the steps of installing the support assembly arc performed using a jackup vessel.
15. The method according to claim 14, wherein the step of turning the platform relative to the transition piece is performed using a number of taglines, each tagline extending between the platform and a winch of the jackup vessel.
Description
BRIEF DESCRIPTION
[0027] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
[0028] FIG. 1 shows a transition piece of an exemplary embodiment of the inventive support assembly;
[0029] FIG. 2 illustrates exemplary stages of the inventive method;
[0030] FIG. 3 illustrates exemplary stages of the inventive method;
[0031] FIG. 4 illustrates exemplary stages of the inventive method;
[0032] FIG. 5 illustrates exemplary stages of the inventive method;
[0033] FIG. 6 illustrates exemplary stages of the inventive method;
[0034] FIG. 7 illustrates exemplary stages of the inventive method;
[0035] FIG. 8 shows an exemplary the platform of the inventive support assembly after installation is complete;
[0036] FIG. 9 shows a partial cross-section through an exemplary embodiment of the inventive support assembly;
[0037] FIG. 10 illustrates an exemplary embodiment of the invention;
[0038] FIG. 11 illustrates an exemplary embodiment of the invention;
[0039] FIG. 12 shows a partial cross-section through an exemplary embodiment of the inventive support assembly;
[0040] FIG. 13 shows conventional offshore wind turbine installations; and
[0041] FIG. 14 shows conventional offshore wind turbine installations.
DETAILED DESCRIPTION
[0042] FIG. 1 shows a transition piece 2 of the inventive support assembly. The transition piece 2 is designed to support a wind turbine as well as wind-powered electrolysis plant and is mounted to a foundation 3 such as a monopile as indicated here. As shown in the diagram, the transition piece 2 comprises an annular arrangement of outwardly-protruding support shelves 10. In this exemplary embodiment, ten equidistantly-spaced support shelves 10 are arranged at the same level around the transition piece 2. The diagram also indicates a ladder assembly 20 which willafter installation is completeallow personnel to move between the platform and a vessel moored to the transition piece 2.
[0043] An installation vessel 6 (indicated schematically) such as a jackup vessel can transport a populated platform 11 to the installation site, for mounting to the transition piece 2. FIG. 2 shows a platform 11 (previously populated with all modules of an electrolysis plant 4) being lowered into place onto the transition piece 2 of FIG. 1. In the exemplary embodiment shown here, ten equidistantly-spaced vertical cut-outs 120 in the mounting sleeve 12 (or central ring) of the platform 11 will allow the mounting sleeve 12 to pass the support shelves 10 while being lowered over the transition piece 2.
[0044] FIG. 3 shows the platform 11 approaching the level of the support shelves 10, and FIG. 4 gives a perspective view of this stage of the assembly procedure. From underneath, FIG. 4 shows the central ring 12 of the platform 11 and indicates radially extending support beams 13 that extend to connection points on the underside of the platform floor. The central ring 12 comprises various radially extending flanges 125, 126 for providing structural strength and for connection to the support beams 13. As can be seen in the diagram, each vertical cut-out 120 is shaped to accommodate or fit around a support shelf 10 so that the platform 11 can be lowered to the level of its final position without initially coming into contact with the support shelves 10. A vertical cut-out 120 extends into the lower flange 126 so that the mounting sleeve 12 can pass over the support shelves 10 when the platform 11 is being lowered onto the transition piece 2.
[0045] FIG. 5 shows an elevation view of the inventive assembly after lowering the platform 11 onto the transition piece 2. The lateral cut-outs 121 in the central ring 12 of the platform structure 11, shown in FIGS. 2-5, are now aligned with the respective support shelves 10. At this stage, the weight of the platform 11 is still carried by the installation vessel crane 60 (as indicated by the lifting cables 63).
[0046] The next stage of the inventive method is to lock the platform 11 to the transition piece 2. This is done as illustrated in FIG. 6, which shows a perspective view of the populated platform 11 still suspended from the crane, and tag lines 61 between the platform 11 and winches 62 (which can be located on the installation vessel). The winches 62 are deployed to pay out and rewind the tag lines 61 as appropriate, in order to effect a controlled rotation R of the platform 11 by the desired amount. This step is also illustrated with the aid of FIG. 7, which shows an inside view in which only the support shelves 10 of the transition piece 2 are visible (the remainder of the transition piece 2 is rendered invisible in order to reveal the inside surface 12S of the platform's central ring 12). When the tag-line winches are actuated as described above, the platform 11 turns to engage the support shelves 10 with their respective lateral cut-outs 121. The angle of rotation is determined by the dimensions of the support shelves 10 and lateral cut-outs 121 as indicated. In this exemplary embodiment, a displacement angle of 5 is sufficient to engage the support shelves 10 with the contact faces 121F of their respective lateral cut-outs 121. The diagram also shows low-friction blocks 124 (comprising a suitable material such as nylon) attached to the inside of the mounting ring, to facilitate turning of the closely-fitting central ring 12 about the transition piece 2 during the rotation step.
[0047] FIG. 8 shows the platform 11 of the inventive support assembly 1 after its installation is complete. The diagram shows the platform 11 populated with an electrolysis plant 4 (i.e., electrolyzer modules and balance of plant modules as described above), a davit crane for general hoisting maneuvers, etc. A wind turbine tower 50 can now be connected to the transition piece 2 in the usual manner, and the completely installed and commissioned wind turbine 5 can then drive the electrolysis plant 4.
[0048] FIG. 9 shows a partial perspective view the transition piece 2, a support shelf 10, and the central ring 12 of the platform 11. In this embodiment, a support shelf 10 has a horizontal contact plate 100 carried by two vertical brackets 101. The upper surface of the contact plate 100 is the contact surface 100F of the support shelf 10 and will receive a contact surface 121F of the mounting sleeve 12. The support shelf 10 is shown inside a vertical cut-out 120, and next to a sleeve portion 12P with a lateral cut-out 121. The diagram indicates how the weight of the platform 11 will be transferred to the transition piece 2 (and down to the foundation 3) when the platform 11along with the mounting sleeve 12is rotationally displaced as shown, causing the support shelf 10 to engage with the lateral cut-out 121 of the sleeve portion 12P.
[0049] FIG. 10 and FIG. 11 illustrate an embodiment of the invention. The simplified schematic diagrams show a portion of the central ring 12 about the transition piece 2. In this embodiment, each support shelf 10 is angled to a small extent, for example the contact surface 100F of a support shelf 10 can be angled by about 10 relative to the horizontal. Each lateral cut-out 120 has a corresponding shape, i.e., with a contact face 121F that is slanted by the same amount. In FIG. 10, the platform 11 has been lowered to an initial level. In the next stage, the platform 11 is turned as described above to rotate the central ring 12 relative to the transition piece 2 (indicated by the horizontal arrow) so that the lateral cut-outs 120 move into place about the respective support shelves 10. In a final step as indicated in FIG. 11, the platform 11 is lowered by a further amount (indicated by the vertical arrow) until the slanted contact face 121F of each cut-out 120 rests on the slanted surface 100F of its corresponding support shelf 10 as shown in the diagram. Additional contact faces 100F, 121F are provided in the lower region of the support feature 10, 121. In this embodiment, the force of gravity ensures that the platform 11 will never disengage from the support shelves 10, even in extreme conditions.
[0050] FIG. 12 shows a partial cross-section through an exemplary embodiment of the inventive support assembly 1. Here, two diametrically opposed support shelves 10 are shown, one on the left-hand side and one on the right-hand side of the diagram. The basic structure of the support shelf can be as described, for example, in FIGS. 1-5 and FIG. 9, although the underlying idea described here can of course apply to various other designs, i.e., that a significant fraction of a support shelf 10 is located in the interior of the transition piece 2. In the exemplary embodiment shown here, only about one third of each support shelf 10 extends beyond the outer surface of the transition piece 2. As the diagram shows, the slanting brackets 101 extend to a considerable distance downward into the interior of the transition piece 2. Here, the lower ends of the brackets 101 meet at an inwardly extending flange 22 positioned at a lower level in the interior of the transition piece 2. The upper ends of the brackets 101 can be welded to the contact plate 100 of the support shelf 10, while the lower ends of the brackets 101 can be welded to the interior flange 22. The flange 22 itself can be supported as appropriate by any suitable fittings (not shown). The diagram also indicates the possible shapes of slits 2 in the transition piece 2 that can be provided to accommodate the vertical brackets 101 and the horizontal contact plate 100 of a support shelf 10.
[0051] As indicated by the exemplary embodiments described above, the inventive support assembly requires only a minor modification to the established transition piece design, namely the addition of the support shelves 10. The platform 11 that rests on the support shelves 10 can have a favorably straightforward structure. Since the platform 11 can be populated at an onshore facility and installed by simply lowering it onto the waiting transition piece 2 and turning it by a small amount, the installation costs of the inventive support assembly 1 are favorably low.
[0052] FIG. 13 shows a conventional offshore wind turbine 5 that exports power to the grid. The wind turbine tower 50 is connected to a transition piece 2, which in turn is mounted to a foundation 3 such as a monopile as shown here. The diagram shows a typical service platform 7 at the base of the wind turbine tower 50, to facilitate personnel access to the tower. A davit crane can be a permanent fixture on the platform 7, for example to assist in hoisting equipment between a service/installation vessel and the service platform 7. The service platform 7 may also have room for a temporary auxiliary power supply, for example during installation of the wind turbine 5, to assist in maintenance routines during the service life of the wind turbine, etc. This relatively compact service platform 7 and transition piece 2 can be assembled and transported as one structure for mounting to the foundation 3.
[0053] FIG. 14 shows an offshore wind-powered electrolysis installation. Here also, the wind turbine tower is connected to a transition piece 9, which in turn is mounted to a foundation. The transition piece 9 can have the same dimensions as the conventional transition piece 2 of FIGS. 1-12 but is extensively modified to add a platform support interface 90 as shown here. The diagram shows a platform 8 that is large enough to accommodate all modules of an electrolyzer plant. To arrive at the required surface area, the platform 8 is realized in this case as a two-storied structure. Since the wind turbine tower must be mounted to the transition piece 9 before the electrolyzer platform 8 is installed, the platform 8 must be assembled (and transported) independently of the transition piece 9. After installation of the wind turbine tower, the platform 8 can be assembled and then populated with the electrolyzer and its balance of plant. This prior art solution requires extensive modification of the established transition piece design which is used widely for conventional power-exporting wind turbines as indicated in FIG. 13, and which is used with only a minor modification in the inventive support assembly 1 as shown in FIGS. 1-12. The prior art structure 8, 9 shown here requires significantly more material than the inventive support assembly 1 and incurs significantly higher installation costs than the inventive approach.
[0054] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. For example, while the support structure lends itself particularly well for an offshore wind-powered water electrolysis installation, the platform of the support structure could equally be relatively small, for example for use as a general service platform of an offshore wind turbine that exports power to the grid. Here also, the ability to twist lock the platform onto the transition piece would simplify the installation procedure of the offshore wind turbine.
[0055] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.
