METHOD FOR BUILDING A METALLIC TOWER FOR A WIND TURBINE

Abstract

Provided is a method for building a metallic tower for a wind turbine, including the steps of: at a manufacturing site, manufacturing hollow cylindric metallic tower sections, wherein the tower sections can be stacked in a longitudinal direction to form the tower, cutting, at least for tower sections whose diameter exceeds a predefined maximum diameter, the tower sections longitudinally into a first number at least two section segments, transporting the section segments to a building site where the tower is to be erected, joining section segments by welding to reconstruct the cut tower sections, and stacking the tower sections to build the tower.

Claims

1. A method for building a metallic, tower for a wind turbine, the method comprising: at a manufacturing site, manufacturing hollow cylindric metallic tower sections, wherein the tower sections are stacked in a longitudinal direction to form the metallic tower; cutting, at least for tower sections whose diameter exceeds a predefined maximum diameter, the tower sections longitudinally into a first number at least two section segments; transporting the at least two section segments to a building site where the tower is to be erected; joining the at least two section segments by welding to reconstruct the cut tower sections; and stacking the tower sections to build the tower.

2. The method according to claim 1, wherein each tower section comprises at least one subsection, wherein manufacturing the subsections comprises: providing a metal sheet, rolling the metal sheet, and welding the rolled metal sheet.

3. The method according to claim 2, wherein multiple subsections are weldingly connected to form a tower section.

4. The method according to claim 1, wherein manufacturing the tower sections comprises adding a flange to each side of the tower sections and/or at least one machining step, and/or painting the tower section.

5. The method according to claim 4, wherein painting the tower sections comprises covering a cutting area where the tower section is cut into the at least two section segments.

6. The method according to claim 1, wherein cutting is performed using a flame cutting machine or a plasma cutting machine.

7. The method according to claim 1, wherein after cutting, the cutting edges are bevelled, V-bevelled from the inside, and/or treated with a primer.

8. The method according to claim 7, wherein welding the section segments is performed from an inside of the tower section to be reconstructed.

9. The method according to claim 1, wherein before welding the section segments to reconstruct the tower sections, a reconstruction tool is used to position the at least two section segments and/or the welding of the section segments to reconstruct the tower sections is performed as submerged arc welding.

10. The method according to claim 1, wherein after welding the section segments to reconstruct the tower sections, the welding area is machined, and/or, if the cutting area had not been painted.

Description

BRIEF DESCRIPTION

[0028] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0029] FIG. 1 shows a flowchart of an embodiment of a method according to embodiments of the invention;

[0030] FIG. 2 shows a manufactured tower section prepared for painting;

[0031] FIG. 3 shows cut section segments;

[0032] FIG. 4 shows a schematic side view of a section segment;

[0033] FIG. 5 shows two adjacent cutting edges of section segments after bevelling;

[0034] FIG. 6 shows a reconstruction tool at the building site;

[0035] FIG. 7 shows a longitudinal welding process using a mobile welding machine; and

[0036] FIG. 8 shows a principle drawing showing the stacking of tower sections to form a wind turbine tower.

DETAILED DESCRIPTION

[0037] Embodiments of the method according to embodiments of the invention provide a simple and cost-efficient process for building a metallic wind turbine tower, in this case made of steel, wherein the tower has tower sections of a large diameter, greater than 5 m, such that greater hub heights are achievable, for example hub heights greater than 80 m. Despite the large diameters, embodiments of the invention allow for easy transportation respecting local logistic restrictions.

[0038] In the embodiment according to FIG. 1, steps S1 to S9 are performed at a manufacturing site, while steps S11 to S16 are performed at a building site where the tower and thus the wind turbine is to be erected.

[0039] First, in steps S1 to S8, tower sections are produced essentially as known from the state of the art, apart from a few minor modifications and the fact that the tower sections' diameter exceeds a maximum diameter, in this case defined according to a legal limit. This means that the tower sections may not be transported as such in a respective country/legislation.

[0040] In step S1, metallic material for the tower sections is provided, in this case stainless steel. In step S2, the steel is cut into metal sheets, which are bevelled for later welding. In step S3, rolling of the metal sheets into a hollow cylindrical form ensues. The welding to form the hollow cylinder takes places in step S4. In step S5, at least flanges are added at both ends of the tower section. If the tower section is made from several hollow cylindric subsections, each providing a part of the tower section height, these subsections are welded together in step S5.

[0041] In an optional step S6, the tower sections are inspected, including non-destructive testing.

[0042] In a step S7, sand blasting of the tower section takes place, for example in a blasting cabin. In step S8, at the tower section's outer surface is painted/varnished. However, before this takes place, for example in a paint cabin, cutting areas around intended cut lines are covered, for example by narrow tapes, such that the cutting areas are excluded from painting.

[0043] This is shown in FIG. 2, which depicts a tower section 1 to be cut into four section segments longitudinally along intended cut lines 2, shown dashed. Before painting, cutting areas 3 are covered, for example by a narrow tape, such that the fraction of the surface excluded from painting remains small, for example less than 5%.

[0044] Returning to FIG. 1, in a step S9, the tower section 1 is cut into the section segments 4, which are exemplarily shown in FIG. 3, using a flame cutting machine or a plasma cutting machine. FIG. 4 shows a side view of a section segment 4, illustrating that not the whole outer surface is painted, but only the central area 5, leaving the cutting edges 6 in the cutting areas 3 free of paint.

[0045] These cutting edges 6 are, also in step S9, bevelled and treated with a primer. As shown in FIG. 5, V-bevelling from the inside 7 is performed, resulting the slanted edges 8. This greatly simplifies welding from the inside 7 as well as gauging from the outside 9 when the section segments 4 are rejoined at the building site, as further explained below. The section segments 4, which fulfil any logistic restriction, are now ready for transport.

[0046] In a step S10, see FIG. 1, the section segments 4 are transported from the manufacturing site to the building site using a standard truck or, depending on the length of the segments 4, using special trucks or transport means.

[0047] In a step S11, the section segments 4 of a tower section 1 which is to be reconstructed are placed in a reconstruction tool 10, as indicated in FIG. 6. The reconstruction tool 10 may, for example, comprise a frame and/or respective holding devices. The section segments 4 are positioned correctly, exploiting the bevelling technique explained above to gauge from the outside 9.

[0048] Returning to FIG. 1, in a step S12, the section segments 4 are re-joined to recreate the tower section 1 by longitudinal welding. The welding is performed from the inside 7 of the tower section 1, exploiting the V-bevel. This is illustrated in FIG. 7, wherein, in this case, a mobile welding machine 11 is used which is only schematically indicated. Submerged arc welding (SAW) may be used. Beginning at one face side of the tower section 1, the cutting edges 6 of the section segments 4 are welded together, as indicated by welding seam 12. The welding machine 11 is moved longitudinally, according to arrow 13, until the other face side is reached.

[0049] After welding, in a step S13 according to FIG. 1, mechanical blasting of the longitudinal welding area is performed using a mechanical roughness tool. This may be done manually. In a step S14, the longitudinal welding area is painted manually, using respective painting tools.

[0050] In an optional step S15, internal components may be added to the reconstructed tower section 1, for example platforms, ladders and the like.

[0051] In step S16, finally, the complete tower sections 1 are stacked to build the tower 14 of the wind turbine, as shown in FIG. 8 and in principle known in the art. A crane 15 and/or another lifting tool may be used. The tower sections 1 may be connected using the flanges.

[0052] Once the tower 14 is erected, the nacelle with the hub may be added and the blades may be mounted to complete the wind turbine.

[0053] Although the present invention has been disclosed in the form of preferred 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.

[0054] 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. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.