Method for assembling and automatically lifting a wind turbine tower

Abstract

The invention relates to a method for assembling and automatically lifting a wind turbine tower, characterised in that different ferrules (3) composed of wedges (4) are formed in situ using robotised elements (10) that travel along circular guides (9). Welding, inspection and painting elements are simultaneously applied to the inside and outside of the ferrule (3), and work is done at two heights by replicating the circular guides (9) and raising same by means of vertical columns (16). As the ferrules (3) are formed, they are raised by a triangle (6) that travels between columns (5) of the automatic lifting system. Subsequently, by horizontally welding ferrules (3) together, a tower section (2) is formed. The method is applied to tubular towers and frustoconical towers that are 6-8 m in diameter and at least 200 m high.

Description

[0001] METHOD OF ASSEMBLY AND AUTHORIZATION OF A WIND TURBINE TOWER

[0002] DESCRIPTION

[0003] Field of the invention

[0004] On-site assembly and self-erecting method for high-rise, large-diameter metal towers.

[0005] Background

[0006] Wind turbines are gaining in power and size. The towers that support them, exceeding 120 m, present problems in logistics, assembly, and dynamic coupling with other wind turbine components. The materials used to manufacture current towers are metal and concrete. The best and cheapest product at ex-works cost is metal, but its on-site assembly requires large cranes, and above 160 m, stocks are either unavailable or very expensive and scarce. Furthermore, the logistics and transportation of current towers are limited to 4.5 m; tower sections cannot exceed these measurements in diameter because they cannot pass under bridges or tunnels.

[0007] For this reason, towers above 120 m in height are usually made of concrete, as prefabrication near the park or even on-site manufacturing allows for diameters larger than the 4.5 m limit and avoids the risk of dynamic coupling. However, these concrete towers still require large cranes, and the total cost of the installed tower increases exponentially with height.

[0008] In a previous study of the state of the art, the following patents are highlighted:

[0009] Document WO2011099915A1 relates to a method for assembling a wind turbine. The tower is assembled by hoisting it using lifting equipment located at the base. Once the tower is hoisted, two sheets are joined by a vertical weld followed by a horizontal weld. The hoisting elements are located inside the tower, and the welding elements are located outside.

[0010] Document W02020148065A1 describes a wind turbine tower formed by a series of prefabricated sheets. Said tower is made of at least two segments connected to each other by a circular weld seam such that their longitudinal axes run substantially collinear with each other.

[0011] Document US2021180568 consists of a method of constructing a steel tower for wind turbines with segments formed by the steps of: processing by cutting and bending, surface treatment and joining by longitudinal welding carried out from the inside of the tower using a mobile welding machine.

[0012] Keystone Tower Systems presents a system for the on-site installation of wind turbine towers on its website. It uses a spiral welding system that creates large tower sections that do not require transportation and are then lifted and assembled with a crane.

[0013] The applicant himself has a previous patent application PCTES2023070033 that describes the authorization system described here.

[0014] The difference between the existing state of the art and the new assembly method is: The system used, which lifts the sections being welded in situ, keeps them suspended during the assembly process.

[0015] Welding and painting, as well as their corresponding inspections, are carried out both on the exterior and interior. All of these elements are protected from the elements and can be removed once the assembly process is complete.

[0016] The assembly line is vertical, adding rings or ferrules in a tower suspended in the air, with clamps that hold the segments in a vertical position, with rails to transport the segments through the gate of a compartmentalized chamber that is removed to allow the segments to pass through, and with a second welding and painting floor to increase effectiveness.

[0017] The new method efficiently meets the transportation and assembly demands of building taller towers with larger base diameters that don't require large cranes for assembly. The solution is to transport the tower in segments, join them on-site using a robotic welding process, and simultaneously hoist the tower sections using a custom-built self-lifting system.

[0018] Description

[0019] The object of the invention is to establish a vertical assembly method, joining several voussoirs, welding and painting them, to form a ring that is added and fixed to the lower part of the suspended tower. And by means of an automatic system and a triangle that goes up and down, the new rings are added and the aforementioned tower is assembled.

[0020] An object of the invention is to construct towers on-site, subject to transportation and assembly limitations. Such towers are assembled on the ground on specific foundations and suspended in the air. They can have a larger diameter and height than current towers.

[0021] Another object of the invention is to carry out the entire assembly process from within the automated system, properly isolating the robotic welding, inspection and painting elements, in an automated process that acts on the inside and outside of the ferrules, at two heights and with fastening and guiding elements for the segments.

[0022] To achieve this, supports and guides are installed on the tower's foundation, an auto-lifting system is set up, the segments (curved sheets) are transported vertically to the assembly site using clamping elements, they slide along the guides until they join together and are welded on-site in a vertical position, forming a ring shell. The entire welding, inspection and painting process is carried out inside a watertight compartmentalized chamber. With the help of the auto-lifting system, the ring shells (already assembled rings) are raised, joining them horizontally to each other until a new tower section is formed. When it is finished, it is hoisted and the next section begins. The tower sections have L-shaped tabs to complete their bolted connection, thus forming the tower.

[0023] From all that has been described, the following advantages emerge:

[0024] This assembly method can accommodate any tower diameter, whether tubular or truncated cone, for example, diameters between 6 and 8 m for towers 200 m high. By providing a larger tower diameter, the dynamic problems arising from the reduction in the tower's natural frequency and its coincidence with the wind turbine rotor frequency are overcome.

[0025] Comparing the technology described with the assembly and erection of concrete towers, production time is considerably reduced by not having to wait for the concrete to set and not having to prestress it.

[0026] Comparing the described technology with the assembly and mounting of steel towers composed of sectors, the number of bolts used and the tightening time are considerably reduced, in addition to eliminating the need for auxiliary cranes for assembly.

[0027] Brief description of the drawings

[0028] Below, a very brief description is given of a series of drawings that provide a better understanding of the invention and are expressly related to an embodiment of said invention, presented as a non-limiting example. Figures 1a, 1b, and 1c show the limitations of truck transport for current towers and the partitioning of new, larger-diameter towers.

[0029] Figure 2 shows the elements used in the assembly process: 2a in elevation and 2b in plan.

[0030] Figure 3 shows the anchoring on a foundation of the elements used for the transfer of the voussoirs.

[0031] Figure 4 shows the base template and the different arrangements of the voussoir supports.

[0032] Figure 5 shows the robotic welding, inspection and painting elements, working at two heights and covered with a compartmentalized chamber.

[0033] Figure 6 shows the composition of a tower section with several ferrules joined together and a detail of their temporary fixation depending on their diameter.

[0034] Figure 7 represents the practical implementation of the assembly of a larger diameter tower section, under a smaller diameter tower section and a nacelle.

[0035] Figure 8 shows the assembly process for a complete wind turbine, comprising tower sections and erecting them. The figure shows sections with a constant cross-section and occasional diameter changes, but the invention also works for conical towers.

[0036] Detailed description

[0037] As shown in Figure 1 a, the limitation in logistics and transport by trucks (1) of the current tower sections (2), is the maximum height (Hmax) or maximum diameter (Dmax) of 4.5 m. The tower sections cannot exceed these measurements because they cannot pass under bridges or tunnels. This conditions the diameter of the current towers to the aforementioned height. To achieve larger diameters, the shells (3) that make up the tower sections (2) must be separated, transported and subsequently joined on site. According to an example practical implementation shown in Figures 1 b and 1 c: a diameter DT of 6.5 m is made up of three sections of 120 e which have a length LT of 5.7m and a height Eh of 2.4m; a diameter D2 of 8m is made up of three sections of 120 ewhich have a length L2 of 7m and a height H2 of 3m. By breaking down the tower section (2) into shells (3) and this in turn into segments (4) they can be transported in trucks (1) without exceeding the maximum height or diameter of 4.5m. Once they have reached the assembly point, the segments (4) are removed from the truck (1) and left ready for use.

[0038] As shown in the elevation and plan of figure 2, the auto-lifting equipment consists of three columns (5) joined by an equilateral triangle (6) where either a tower section (2) or the upper ring nut (3) of the first tower section is anchored. The triangle (6) goes up and down between the columns (5) fixing itself to the outer flange of the upper ring nut and allowing the new ring nuts (3) to be added from the bottom. The practical implementation of the auto-lifting system can vary by increasing the number of columns (from three to four) and varying the connecting piece (from a triangle to a square) where either the tower sections (2) or the ring nuts (3) are anchored. In the space existing at the base of the columns (5) the voussoirs (4) move in a vertical position held by means of clamps (7) and running through their corresponding transverse guides (8).At the center of the automated system there are two concentric circular guides (9) along which the robotic elements for welding, painting and inspection (10) move. These robotic elements (10) are protected from the elements by a compartmentalized chamber (11) that surrounds them, while they rotate circularly on their concentric guides (9).

[0039] Figures 3a and 3b show a closer look at the positioning of the voussoirs (4). The clamps (7) hold the voussoirs (4) vertically. Both the transverse guides

[0040] (8) as the circular guides (9) are placed on the foundation (12) of the tower. This fixation provides the stability required to proceed with its welding and makes the process faster by sliding and positioning new segments (4') while the robotic equipment acts on the first segments (4).

[0041] Figure 4a shows the foundation (12) of the tower and its bolts (13). Around the bolts (13) and attached to them, a template (14) is arranged that supports the guides (8 and 9) of figure 3. This template (14) is temporary, has the shape of a ring and supports and fixes the voussoirs (4) that can be cylindrical or truncated cone. To keep the voussoirs (4) vertical while they are welded to form the ferrules (3), different supports (15) are used with different diameters coinciding with the lower diameter of each tower section, as shown in figure 4c.

[0042] As shown in Figure 5a, the robotic elements (10) can be increased in number and work at two heights. To achieve this, the circular guides are replicated.

[0043] (9) raising them by means of vertical columns (16) to a height sufficient to allow the incorporation of new segments (4). The combination of work at two heights allows alternating welding with the finishing and painting processes, reducing assembly times. On the other hand, three segments (4) are necessary to compose a ferrule (3), so two robotic elements (10) can operate on each of the circular guides (9): Two inside the sections of the tower and two outside. Figure 5b shows how all the elements are covered with a compartmentalized chamber (11) that has a gate that is withdrawn when the segments (4) pass through and when the ferrules (3) are raised, and that keeps the equipment in optimal conditions for its work.

[0044] Figure 6a shows a tower section (2) made up of several shells (3). To optimize the processes, the segments (4) that make up a shell are rotated with respect to the previous ones so that the vertical weld beads (17) do not coincide. Once a shell (3) is composed, it is horizontally welded to the shell immediately above it, forming a horizontal weld bead (18). The process is repeated, raising the shells (3) formed by means of the auto-izing system until a tower section (2) is completed. The robotic elements (10) are inside the chamber (11) to achieve the necessary tightness during the welding, inspection and painting processes. Figure 6b clearly shows how the upper and lower shells of each tower section (2) have an L-shaped external flange (19) where the auto-izing systems are anchored.As shown in the detail of figure 6c, the outer tab (19) of the ferrule (3) is fixed with the different concentric supports (15) supported on the template (14) of figure 4. The inner tab (20) is the standard joint for conventional tower ferrules.

[0045] The proposed assembly method has the following steps:

[0046] Install a hoisting system with its three columns (5) and place a nacelle (21) on the triangle (6). Alternatively, you can start with a nacelle (21) and a tower section (2). Raise them using the hoisting system.

[0047] Mount the template (14), the various concentric supports (15), the transverse guides (8) and the circular guides (9) on the bolts (13) of the tower foundation (12). The transverse guides (8) work in pairs and there are three guides arranged between the three columns (5) that converge on the two circular guides (9) concentric with the foundation (12) and with the auto-lifting system.

[0048] Vertically move at least two voussoirs (4) and preferably three, by means of the clamping clamps (7), removing the door of the compartmentalized chamber (11) to allow its passage, joining the voussoirs (4) wall to wall, composing a ring (3) that is equidistant between the two circular guides (9). Fix them to the supports (15) using the support appropriate to their diameter.

[0049] Place the robotic elements (10) on the circular guides (9) and proceed with the vertical welding bead (17), finishing and painting the ferrule (3). Lift the first ferrule with the triangle (6), holding it with the outer tab (19), leaving it suspended in the air and repeat the process with the second ferrule (3), welding it to the first ferrule with a horizontal welding bead (18).

[0050] The process is repeated until a tower section is formed (2).

[0051] When a new section of tower (2) is finished, it is fixed to the different supports (15) anchored with the outer tab (19) of the lower ferrule and the triangle (6) is released to lower it and repeat the process.

[0052] The template (14), concentric supports (15) and guides (8 and 9) are removed before anchoring the tower to the foundation (12).

[0053] As shown in Figure 8, in this practical embodiment the nacelle (21) and a tower section (2) are pre-assembled. The shells (3) formed with the assembly method described are of a larger diameter than the initial tower section, which has the maximum permitted diameter of 4.5 m. The triangle (6) supports the tower section (2) and the nacelle (21) from above and the shells (3) are added below, which are formed with robotic welding. When the new tower section is finished, it is fixed to its corresponding support (15) depending on its diameter and the triangle (6) is released to lower it and repeat the process.

[0054] When more than one tower section (2) has been composed from the triangle (6), extension arms (22) are extended and fixed to the protruding tabs (19) existing in the upper and lower ferrules of each tower section (2), all as shown in figures 8a, 8b and 8c. The change in diameter between the first tower section (2) with a diameter of 4.5m and the second tower section (2) with a larger diameter depending on the structural needs of the tower is solved with a transition piece (23) that goes from a smaller diameter to a larger diameter.

Claims

CLAIMS 1 - Method of disassembly and self-assembly of the tower of a wind turbine that has a self-assembly system with at least three columns (5) and a triangle (6), and a foundation (12) with its corresponding bolts (13), characterized in that: - A compartmentalized chamber (11) is installed inside the auto-lifting system, on which there is a nacelle (21) resting on the triangle (6), - on the bolts (13) protruding from the foundation (12) a template (14) and concentric supports (15), transverse guides (8) and circular guides (9) are mounted, all of which are between the columns (5), concentrically with the foundation (12), - at least two voussoirs (4) are moved vertically, held by clamps (7) which run along the transverse guides (8) to the concentric supports (15), - a door is removed from a compartmentalized chamber (11) to allow the passage of the voussoirs (4), forming with them a ring (3) that is equidistant between the two circular guides (9) and fixed to the supports (15), - some robotic elements (10) move on the circular guides (9) and the vertical welding bead (17) is finished and the ferrule (3) is painted inside the compartmentalized chamber (11), - the first ferrule (3) is raised, which has an external tab (19) for fastening it to the triangle (6) and is screwed to the nacelle (21), and the process is repeated with the second ferrule (3), welding it to the first ferrule with a horizontal welding bead (18), - the process is repeated until a tower section (2) is achieved and different tower sections (2) are joined together using extension arms (22) until all the tower sections are completed, - the template (14), the concentric supports (15), the transverse guides are removed (8), the circular guides (9) and the compartmentalized chamber and the tower with the largest diameter to the conventional one is anchored to the foundation (12). 2- Method of assembly and auto-lifting of the tower of a wind turbine according to the previous claim, characterized in that the robotic elements (10) work at two heights replicating the circular guides (9) and raising them by means of vertical columns (16) to a sufficient height to allow the incorporation of the different voussoirs (4) at the bottom. 3- Method of assembly and automatic lifting of the tower of a wind turbine according to the first claim, characterized in that two or more robotic elements (10) operate for each of the circular guides (9), two inside the ferrule (3) and two outside the ferrule (3), being able to separate the welding, finishing and painting operations in each of the robotic elements. 4- Method of assembly and self-lifting of the tower of a wind turbine according to the first claim, characterized in that tower diameters greater than 4.5 m are composed, with sections of tubular tower and truncated cone tower and transition pieces (23) are used to pass through intermediate diameters depending on the structural needs of the tower. 5- Method of assembly and self-lifting of the tower of a wind turbine according to the first claim, characterized in that the segments (4) that make up a ferrule are rotated with respect to the previous ones so that the vertical weld beads (17) do not coincide, once a ferrule (3) is composed, it is welded horizontally to the immediately superior ferrule, forming a horizontal weld bead (18). 6- Method of assembly and self-lifting of the tower of a wind turbine according to the first claim, characterized in that when a new section of tower (2) is finished, everything is fixed to its corresponding support (15) through the outer tab (19) and the inner tab (20) of the lower ring nut is released, lowering the triangle (6) and repeating the process.

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