EP2857615A1

EP2857615A1 - Mounting method and mounting device of a concrete tower formed with precast pieces

Info

Publication number: EP2857615A1
Application number: EP13187281.4A
Authority: EP
Inventors: Francisco Jose Saenz Saenz
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-10-03
Filing date: 2013-10-03
Publication date: 2015-04-08
Also published as: WO2015049363A1

Abstract

Mounting method of a hollow tower (11) structured in vertical sections (13) formed by concrete precast pieces (15), comprising the steps of: installing a primary module (14) of an auxiliary tower (12), coupling a deliverer platform (27) to its top and a mounting gateway (19) to its lower base; mounting those vertical sections (13) of the tower accessible from the deliverer platform (27); raising the primary module (14) in the height of a vertical section (13), adapting the surface of the mounting gateway (19) to the inner surface of the next vertical section (13) and assembling a new module (26) to the auxiliary tower (12); placing the precast pieces (15) of the next vertical section (13); joining the concrete precast pieces (15) of the next vertical section (13) with the precast pieces (15) of the lower section, and repeating steps up to complete the mounting.

Description

FIELD OF THE INVENTION

The present invention relates to hollow concrete towers formed with precast pieces, especially but not exclusively, such as those used in wind turbines and more in particular to a mounting method and a mounting device thereof.

BACKGROUND

Nowadays there are numerous industrial applications which require the building of tall concrete towers structured with precast pieces.
Thus, for example, in the wind power industry there is a strong demand for towers as the ones described in the paragraph above to support the nacelle and the blades of high power wind turbines.
In addition, in this technical field, there is a growing tendency of increasing the tower's height for improving the performance of the wind turbines, in such a way that some of the more modern towers reach heights between 120 m and 200 m.
Concrete towers with said features are known in the art.
WO 03/069099 describes a tower structured by a set of sections formed by several precast pieces where vertical tensor cables are used as primary attachments means of the precast pieces.
WO 2006/111597 describes a tower structured by a set of precast pieces of reduced thickness stiffened by an internal structure of horizontal and vertical ribs where horizontal and vertical tensor cables are used as attachments means of the precast pieces.
The basic problems of such towers are: the mounting complexity, which frequently makes necessary the use of big cranes, and the maintenance costs.
The presence of wind can make complicate both tasks, especially if they are performed in the upper part of the tower located, as previously discussed, at considerable height from the floor. As is well known, wind turbine towers can be located in places difficult to be accessed by cranes capable of lifting heavy loads to great heights.
The present invention is directed to solving that problem.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a mounting method of a hollow tower without using a conventional crane and a tower mounted by this method, the tower being structured in a plurality of vertical sections formed by several precast pieces.
Another object of the present invention is to provide a mounting device of a hollow tower structured in a plurality of vertical sections formed by several precast pieces.
Said mounting device according to the invention comprises:

an auxiliary tower provided with a primary module and at least one additional module, being said primary module provided in its turn with lifting means,
a deliverer platform provided in the top part of the device, and a
mounting gateway.

In one aspect, these and other objects are achieved by a method comprising steps of:

a) installing a primary module of an auxiliary tower provided with means for its lifting in parallel to the mounting of vertical sections of the tower in the center of its intended location, coupling a deliverer platform to its top and a mounting gateway to its lower base, the deliverer platform being provided with means for moving the precast pieces, the mounting gateway being provided with retractable means to adapt its surface to the inner surface of the hollow tower in each vertical section;
b) mounting those vertical sections of the tower accessible from the deliverer platform in its initial position placing the concrete precast pieces in their intended location and joining them together;
c) raising the primary module in the height of a vertical section of the tower, adapting the surface of the mounting gateway to the inner surface of the next vertical section and assembling a new module to the auxiliary tower by its base;
d) placing the concrete precast pieces of the next vertical section of the tower in the location intended for them using the deliverer platform;
e) joining the concrete precast pieces of the next vertical section of the tower with the concrete precast pieces of the lower section, accessing to their attachment means from the mounting gateway;
f) repeating steps c), d) and e) up to complete the mounting of the tower;
g) removing the deliverer platform and the auxiliary tower lifting means.

The method of the invention is applicable to any hollow tower structured in a plurality of vertical sections formed by several precast pieces in which the attaching means of the precast pieces are accessible through the interior of the tower.
In one embodiment, the tower is structured in a plurality of vertical sections formed by several precast pieces, configured with outer and inner walls, upper and lower horizontal bases and side walls, comprising on the one hand interlocking means and on the other hand an anchoring element embedded in the inner wall having an upper conduit and a lower conduit for the passage of tensor cables.
With this structure, the joining operations of the concrete precast pieces, consist of, on one hand, on the sealing of the interlocking means of the concrete precast pieces located on two adjacent vertical sections with a grout which is poured through a hole accessible from the interior of the tower and, on the other hand, joining each concrete precast piece of a vertical section to the adjacent concrete precast pieces of the lower section by passing a tensor cable by, respectively, their upper and lower conduits and forming with it a tensioning ring that joins the precast pieces of two adjacent vertical sections.
In another aspect, the above mentioned objects are achieved with a tower comprising the tower mounted by the mentioned method and the auxiliary tower used in the mounting. In the case of a wind turbine tower the auxiliary tower provides an access means both to the interior of the tower and to the nacelle and turbine blades to perform maintenance tasks.
In another aspect, the above mentioned objects are achieved with a mounting device comprising:

an auxiliary tower disposed in the centre of the hollow tower comprising a primary module formed by a lattice of metal bars and various additional modules also formed by a lattice of metal bars that are assembled to the auxiliary tower by its base to increase its height in parallel to the mounting of the tower using appropriate lifting means;
a deliverer platform of precast pieces, coupled to the top of the primary module so that it can rotate 360°, comprising a box girder with at least two hoists at its ends for moving two concrete precast pieces from a certain locations outside the tower to a vertical section of the same and control means for controlling the positioning of the precast pieces in their intended locations while they are not yet stably joined to the precast pieces of the lower section;
a mounting gateway fixedly coupled to the primary module for facilitating the performance of mounting tasks from the interior of the tower, comprising means for adapting its surface to the inner surface of the tower in different vertical sections.

Other characteristics and advantages of the present invention will be clear from the following detailed description of embodiments illustrative of its object in relation to the attached Figures, in which identical or similar elements are identified with the same reference numbers.

BRIEF DESCRIPTION OF THE FIGURES

Figures 1a and 1b are respectively a plan view and a perspective view of an embodiment of a precast piece used to form the tower mounted according with the method and the device of the invention.
Figure 2 is a view of Figure 1b along the plane A-A illustrating the interlocking means of a precast piece.
Figure 3 is a view of Figure 1b along the plane B-B illustrating the anchoring element of the tensor cables which link together the precast pieces.
Figures 4a and 4b are schematic views illustrating two embodiments of towers that can be mounted according with the method and the device of the invention.
Figure 5 is a perspective view illustrating the arrangement of the tensor cables of the precast pieces of the concrete tower mounted according with the invention to form the tensioning rings that join two contiguous vertical sections of the tower.
Figure 6 shows schematic elevation and plan views of the tower mounted according with the method of the invention and of its mounting device.
Figures 7a and 7b are schematic elevation and plan views of an additional module of the auxiliary tower of the mounting device.
Figure 8 is a schematic plan view of the mounting gateway of the mounting device.
Figures 9a and 9b are schematic plan and elevation views of the deliverer platform of the mounting device.
Figure 9c is a side elevation view of a joist of the deliverer platform.
Figures 10a-10j are schematic elevation and plan views of the tower mounting process and of the mounting device illustrating the basic steps of the mounting method of the tower of the invention.
Figures 11a-11i are schematic plan views illustrating the step of placing the precast pieces in a vertical section of the tower.
Figure 12 is a schematic elevation view of the precast pieces raising step according to an alternative embodiment of the mounting method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The tower (Figs. 1-5)

We will firstly describe the particular structure of the tower 11 which will be used to describe the method and device of the invention.
The tower 11 of the invention is a tower structured in vertical sections 13, each section being formed by several precast pieces 15.
The precast pieces 15, configured with outer and inner walls 51, 53, upper and lower horizontal bases 57, 55 and side walls 59, 61, have, preferably, a dowel shape as illustrated in Figures 1a, 1b and are made with high strength concrete and inner steel bars 16.
The terms exterior, interior, upper and lower and lateral applied to the precast pieces 15 shall be understood in reference to their position in the tower 11.
Using dowel-shaped precast pieces 15, the tower 11 may have a frusto-conical or cylindrical shape as illustrated in Figures 4a and 4b. In the second case, all the vertical sections 13 have the same diameter while in the first case they have different diameters and different number of precast pieces 15 at different vertical sections 13, for example 6 precast pieces in the first vertical section and 2 precast pieces in the last vertical section.
Preferably, the height of the precast pieces 15 is comprised between 1.2 - 3m and the ratio width/height is greater than 2. They are therefore precast pieces 15 of a relatively small size.
The tower 11 is structured with the precast pieces 15 of each vertical section 13 mounted staggered with respect to the pieces of the lower section (see Figure 5) and joined by two attachment means: on the one hand, interlocking means as vertical attachment means between the precast pieces 15 of a vertical section 13 with the precast pieces of the lower vertical section; on the other hand tensor cables 17 to link together by the inside the tower 11 the precast pieces 15 of a vertical section with the adjacent precast pieces of the lower section.
The interlocking means comprise two female recesses 31, 33 and two male inserts 35, 37 located respectively on the lower and upper bases 55, 57 of the precast pieces 15. Preferably the male inserts 35, 37 are made of steel and configured with a cross-shaped head 36 and a shank 40 which is screwed into a sheath 41 embedded in the precast pieces 15. The joints between male inserts 35, 37 and female recesses 31, 33 are filled with slurry of high strength concrete which is poured through holes 39 (see Figure 2).
Male inserts 35, 37 absorb part of the shear stress to which the tower 11 is subjected and the staggering of the precast pieces 15 of a vertical section 13 of the tower 11 with respect to the precast pieces 15 of the lower vertical section implies that the two female recesses 31, 33 of a precast piece 15 engage with the male inserts 37, 35 of two different precast pieces 15 of the lower vertical section thereby enhancing the strength of the tower 11.
The precast pieces 15 comprise anchoring elements 21 for tensor cables 17 which are embedded in the precast pieces 15 by their inner wall 53. These anchoring elements 21 comprise an upper conduit 23 and a lower conduit 25 for the passage of tensor cables 17. A tensor cable 17 passes through the upper conduits 23 of the precast pieces 15 of the central vertical section 13 and through the lower conduits 25 of the precast pieces 15 of the lower section and another tensor cable 17 passes through the lower conduits 25 of the precast pieces 15 of the central vertical section 13 and by upper conduits 23 of the precast pieces 15 of the upper section. To avoid crossing of cables 17, the upper and lower conduits 23, 25 are located at a different distance from the inner wall of the precast pieces 15 (contrary to the embodiment shown in Figure 3). With this provision, the tensor cables 17 allow "tying" two vertical sections 13 of the tower 11.
Once tensioned the tensor cables 17 by, for example, a portable electric tensioning pump or a portable mono-cable tensor they are arranged in the form of a ring which starts and ends at the same point in which is placed a double cone terminal (a cone for the start of the cable and other for the ring closure).

The mounting device of the tower (Figs. 6-9)

The mounting device of the tower 11 is formed by an auxiliary tower 12, a deliverer platform 27 and a mounting gateway 19.
The auxiliary tower 12 comprises a primary module 14 formed by a lattice of metal bars and additional modules 26 that are assembled to the auxiliary tower by its base in the lifting steps of the auxiliary tower 12. Additional modules 26 are formed by a lattice of metal bars divided in two parts to facilitate its assembly in each lifting step of the auxiliary tower 12 as will be discussed below.
The deliverer platform 27, that is coupled to the top of the auxiliary tower 12 so that it can rotate 360 degrees about it, comprises a box girder 71 of great inertia with two hoists 73, 75 at their ends provided with an engine power appropriate for the structure of the tower 11 which are arranged for hoisting (more particularly raising) two precast pieces 15 simultaneously to give balance to the system. It also comprises four auxiliary arms 77 intended to control that the precast pieces 15 are maintained in their position until they are joined to other precast pieces 15 by the tensor cables 17.
Figure 9c shows one possible embodiment of the invention in which each one of the hoists 73, 75 comprise trolleys 80 provided with rollers 81 in contact with the box girder 71, said rollers 81 are provided with a movement mechanism (not shown in the figures) which, when operated, make the rollers 81 rotate and consequently forces the trolleys 80 to move along the main direction of box girder 71 to a certain desired position. Attached to trolleys 80 there is an intermediate member 82 to which an engine is affixed (not shown). Said engine is operable to wind and unwind a wire 83, with one of its ends attached to the engine and the other one attached to a hook 84, being said hook 84 intended to fasten a precast piece 15 to be hoisted.
Optionally the engine (and consequently the hook 84 which is attached to the wire 83), can slide along the intermediate member 82, for example by means of a first pinion rack arrangement 85, to obtain a more precise positioning of the hoist 73, 75. The sliding movement of the engine and hook 84 along the intermediate member 82 is represented in figure 9c with dotted lines.
An additional rack 86 can be disposed at the bottom part of the box girder 71 and additional pinions (not shown) can be provided in the trolleys 80 to form a second pion rack arrangement intended to smooth the movement of the trolleys 80 along the box girder 71.
This movement of hoist 73, 75 (and more precisely of the hook 84) is necessary for mounting towers in which the diameter of the vertical sections 13 vary with height, for example the frusto-conical tower shown in Fig. 4a.
Auxiliary arms 77 can be optionally provided at their ends with hoists 73, 75, substantially identical to those described in connection with the box girder 71.
The mounting gateway 19 comprise several radial telescopic beams 79 which can be retracted during the lifting of the auxiliary tower 12 to conform to the inner surface of the tower 11. Above the telescopic beams 79 will slide several stretches of "tramex" type, formed by a lower bearing part and an upper part. They are 10cm wide stretches, which are attached by pins in a hinge mode. When receding the telescoping beams 79 the stretches will fall one by one, applying a delay to the telescopic beams 79 in order to avoid that they hit between them.
The mounting gateway 19, structured in three pieces, allow operators perform various operations for joining the precast pieces 15 during the mounting process of the tower 11.
In the case of wind turbine towers, the auxiliary tower 12 together with the mounting gateway 19 will remain in the interior of the tower 11 after its mounting as it can be used to hold the ladder and other equipment.

The mounting method of he tower (Figs. 10-12)

In a first step (Figs. 10a-10d) the primary module 14 of the auxiliary tower 12 is mounted in the center of the intended location for the tower 11 on a base 10 with the deliverer platform 27 coupled to its top and the mounting gateway 19 fitted in a position close to its lower base.
In a second step, not shown in the Figures, the first vertical sections of the tower which are accessible to the mounting device in its initial position are mounted.
After that a three-step cycle follows: rising the auxiliary tower 12 the height of a vertical section of the tower 11, placing the precast pieces 15 of the following vertical section, and joining these precast pieces 15 with the precast pieces of the lower section. Figures 10e-10g illustrate the second step of the cycle.
Figure 10e shows the mounting device arranged at the appropriate height for initiating a cycle after the mounting of four vertical sections of the tower 11.
Figure 10f shows the deliverer platform 27 of the mounting device lifting two precast pieces 15.
Figure 10g shows the deliverer platform 27 of the mounting device placing two concrete precast pieces 15 over the last section of the tower 11. In one embodiment, this step is performed as illustrated in Figures 11a-11i lifting a pair of precast pieces 15 from particular locations outside of the tower 11 and rotating the deliverer platform 27 to place them in their proper position over the last section of the tower 11. This embodiment of the mounting method is applicable to a tower 11 structured with an even number of precast pieces 15 in each vertical section 13.
Figures 10h-10j illustrate the first step of the cycle mentioned.
Figure 10h shows the auxiliary tower 12 arranged to rise on the height of a vertical section 13 of the tower 11 by using stabilizer arms 18, 18' supported on the vertical sections 13 of the tower 11 already mounted.
Figure 10i shows the auxiliary tower 12 in its new position. The elevation is performed by a hydraulic or an electric system.
Figure 10j shows the auxiliary tower 12 with a new additional module 26 assembled thereto.
Figure 12 is a schematic elevation view of the lifting of precast pieces 15 during the placing of said precast pieces 15 over the last section of the tower (step d), according to an alternative embodiment of the of the mounting method of the invention, in which precast pieces to be raised are provided with stabilizer wheel arrangements 90 in order to slide along the external walls of the vertical sections 13.
Although the present invention has been described in connection with various embodiments, it will be appreciated from the specification that various combinations of elements, variations or improvements therein may be made, and are within the scope of the invention.

Claims

Mounting method of a hollow tower (11) structured in a plurality of vertical sections (13) formed by several concrete precast pieces (15) which are provided with joining means between them, the joining means being accessible from the interior of the tower (11), the method comprising steps of:
a) installing a primary module (14) of an auxiliary tower (12) provided with means for its lifting in parallel to the mounting of vertical sections of the tower (11) in the center of its intended location, coupling a deliverer platform (27) to its top and a mounting gateway (19) to its lower base; the deliverer platform (27) being provided with means for moving the concrete precast pieces; the mounting gateway (19) being provided with retractable means to adapt its surface to the inner surface of the hollow tower (11) in each vertical section (13);

b) mounting those vertical sections (13) of the tower accessible from the deliverer platform (27) in its initial position placing the precast pieces (15) in their intended location and joining them together;

c) raising the primary module (14) in the height of a vertical section (13) of the tower (11), adapting the surface of the mounting gateway (19) to the inner surface of the next vertical section (13) and assembling a new module (26) to the auxiliary tower (12) by its base;

d) placing the precast pieces (15) of the next vertical section (13) of the tower (11) in the location intended for them using the deliverer platform (27);

e) joining the concrete precast pieces (15) of the next vertical section (13) of the tower (11) with the precast pieces (15) of the lower section, accessing to their attachment means from the mounting gateway (19);

f) repeating steps c), d) and e) up to complete the mounting of the tower (11);

g) removing the deliverer platform (27) and the auxiliary tower (12) lifting means.
Mounting method according to claim 1, wherein the precast pieces (15) of each vertical section (13):
- are configured with outer and inner walls (51, 53), lower and upper horizontal bases (55, 57) and side walls (59, 61);

- comprise, except in the first section, two female recesses (31, 33) in its lower base (55) and, except in the last section, two male inserts (35, 37) in its upper base (57), which are configured so that the male inserts (35, 37) of a vertical section can be arranged with play within the female recesses (31, 33) of the upper section;

- comprise an anchoring element (21) embedded in the inner wall (53) with an upper conduit (23) and a lower conduit (25) for the passage of tensioning cables (17).
Mounting method according to claim 2, wherein said upper and lower conduits (23, 25) are located at different distances from the inner wall (53) of the precast pieces (15).
Mounting method according to any of claims 2-3, wherein in step d) the concrete precast pieces (15) of the vertical section (13) are mounted staggered with respect to the concrete precast pieces (15) of the lower portion so that each concrete precast piece (15) of the vertical section (13) rests on two concrete precast pieces (15) of the lower section settling with them at least a joint arrangement between a female hole of the first and a male insert of the second.
Mounting method according to claims 2-4, wherein in step e);
- the joints between the female recesses (31, 33) of the vertical section (13) and the male insert (35, 37) of the precast pieces (15) of the lower section are sealed with a grout which is poured through a hole (39) disposed on the precast pieces (15);

- each precast pieces (15) of the vertical section is joined with the adjacent concrete precast pieces (15) of the lower section by passing a tensor cable (17) by, respectively, the upper and lower conduits (23, 25) and forming with it a tensioning ring that join said pieces.
Mounting method according to claims 2-5 wherein the height of said concrete precast pieces (15) is comprised between 1.2-3m.
Mounting method according to claims 1-6 wherein in step d), the precast pieces (15) to be lifted are provided with stabilizer wheel arrangements (90) for sliding along the external walls of the vertical sections (13).
Wind turbine tower characterized in that comprises a tower (11) mounted by the method of any of claims 1-6 and the auxiliary tower (12) used in the mounting.
Mounting device of a hollow tower (11) structured in a plurality of vertical sections (13) formed by several concrete precast pieces (15) characterized by comprising:
- an auxiliary tower (12) disposed in the centre of the hollow tower (11) comprising a primary module (14) formed by a lattice of metal bars and various additional modules (26) also formed by a lattice of metal bars that are assembled to the auxiliary tower (12) by its base to increase its height in parallel to the mounting of the tower (11) using appropriate lifting means;

- a deliverer platform (27) of precast pieces (15), coupled to the top of the primary module (14) so that it can rotate 360°, comprising a box girder (71) with at least two hoists (73, 75) at its ends for moving two concrete precast pieces from a certain locations outside the tower (11) to a vertical section (13) of the same and control means for controlling the positioning of the precast pieces (15) in their intended locations while they are not yet stably joined to other precast pieces (15);

- a mounting gateway (19) fixedly coupled to the primary module (14) for facilitating the performance of mounting tasks from the interior of the tower (11), comprising means for adapting its surface to the inner surface of the tower in different vertical sections (13).
Mounting device according to claim 9 wherein the deliverer platform (27) is provided with auxiliary arms (77), intended to control that the precast pieces (15), while said precast pieces (15) are maintained in their position until they are joined.
Mounting device according to claim 10 wherein the auxiliary arms (77) are provided at their ends with hoists (73, 75).
Mounting device according to any of claims 9 to 11, wherein each one of the hoists (73, 75) comprise trolleys (80) provided with rollers (81) in contact with the box girder (71), being said rollers (81) provided with a movement mechanism which, when operated, make the rollers (81) rotate and forces the trolleys (80) to move along the main direction of box girder (71).
Mounting device according to claim 12, wherein the trolleys (80) are attached to an intermediate member (82) to which an engine is affixed, being said engine operable to wind and unwind a wire (83), with one of its ends attached to the engine and the other one attached to a hook (84), being said hook (84) intended to fasten a precast piece (15) to be hoisted.
Mounting device according to claim 13, wherein the engine can slide along the intermediate member (82), to obtain a more precise positioning of the hoist (73, 75).
Mounting device according to any of claims 12 to 14, wherein an additional rack (86) is disposed at the bottom part of the box girder (71) and additional pinions are provided in the trolleys (80) to form a pinion rack arrangement, intended to smooth the movement of the trolleys (80) along the box girder (71).