MX2008003787A - Support arm, cylindrical-parabolic solar collector support and method of producing said arm - Google Patents

Abstract

The invention relates to a support arm for a cylindrical-parabolic collector, which is intended to be coupled to a central body (1) of the collector in the form of a bracket in a direction that is essentially perpendicular to a focal line (2) of the collector. The inventive arm takes the form of a wedge comprising:a first side (10) which is equipped with support devices (11) for supporting at least one mirror (3), a second side (20), and a third side (30) which is equipped with support devices (31) such that the arm is supported by the central body (1). The arm is formed by at least one press-formed plate such as to produce a resistant structure that provides stiffness and a carrying capacity by means ofa plurality of ribs (42) which form a lattice comprising a plurality of laminar segments (41) between said ribs.

Description

SUSTAINANCE ARM, SOLAR COLLECTOR SUPPORT CYLINDER- PARABOLIC AND PROCESS FOR MANUFACTURING THE ARM Field of the invention The invention relates to a component and a method of manufacturing said component used in thermal solar plants, in which by means of optical concentration it is heated a fluid (air, water vapor, oil or salts). This fluid moves a turbine, or in turn heats another fluid that is responsible for carrying out this mission. However, the collectors to be described can also be used in combination with photovoltaic panels.

BACKGROUND OF THE INVENTION Within the different types of solar thermal plants are the solar plants of parabolic trough collectors. In this type of plants the thermal fluid passes through a straight pipe located in the very center of an extruded parabola. In turn, this parabola, whose longitudinal axis can be oriented in a north-south or east-west direction, is capable of turning on a single axis to optimize the incident radiation in the collector's opening area. Normally the dimensions of a collector of this type are usually in the order of 100-150 meters in collectors of the latest generation. These collectors, which move by a hydraulic mechanism, are composed of several segments whose length is around 12 meters. In the state of the art, several methods can be distinguished for the manufacture of the arms: 1. Arms made from welded tubes: Until now, the arms in which the mirrors are supported have been manufactured from welded tubes each other, forming a small lattice. However, this manufacturing process, which at the end provides a light and resistant structure, poses two fundamental problems: - The labor associated with cutting and welding the pipes makes the final product considerably more expensive. - The precision obtained in the points of support of the mirrors is not enough to support the mirrors directly. For this reason it is necessary to use intermediate metal pieces attached to the arm by means of sliders that are the ones that finally adjust to the desired position with the help of a tool. This operation also has its repercussion on the final cost of the piece. 2. Other alternatives: For the manufacture of arms to support the mirrors of parabolic trough collectors there are other alternatives among which we can highlight: - The use of fiber panels, sandwich panels or similar to generate structures that are very light and resistant enough . - Use of continuous structures, which avoids the use of arms. Likewise, the arms must comply with a series of characteristics: 1. Geometrical characteristics: Depending on the loads for which the collector is dimensioned, the position of the latter within the field and the measurements of the central box and the primitive parabola that form the mirrors, there are different arrangements of the bars to form the arm. 2. Physical characteristics: Among the most important can be highlighted: - Weight of the arms: Between 10-14 kg / piece. - Surface treatment: Hot galvanized. - Types of profiles used: normally tubular profile, thin-walled (thickness 1-2 mm). In this type of power plant the collector field, that is, the set of all the collectors that collect the solar radiation to heat the oil is a fundamental part. The collectors in which the mirrors are supported are made of metal structure, usually galvanized steel, and must meet the following requirements: - On the one hand, they must provide sufficient precision to position the mirrors in such a way that they concentrate all the radiation in the geometric focus of the theoretical parable. - On the other hand, and given the enormous dimensions that these plants usually have, the metallic structure must be cheap, simple to manufacture and durable. Throughout the history of these plants, different types of structures have been developed capable of satisfying, to a greater or lesser extent, these requirements. It can be distinguished fundamentally, between two types of support structure. - Collectors made based on what could be called "spatial structure". In these collectors, the support structure forms a continuum that extends throughout the back part of the parabola. In this type of structure there is no distinction between central body and arms, forming a monobloc whole. - Collectors formed by a central body and arms that support the mirrors. In this type of collectors the structure can be separated into two parts. On the one hand, the central body, which bears the loads of flexion and torsion fundamentally. This central body can be made of welded tube or by means of a bar structure. To this central body, arms are tied, which are responsible for supporting the parabolic mirrors. The invention relates to these arms to the central body and to the method of manufacturing said arms.Description of the invention A first aspect of the invention relates to a cylinder-parabolic collector support arm configured to be coupled to a central body of the collector as a bracket, in a direction substantially perpendicular to a focal line of the collector, having said arm a wedge shape having: a first side provided with support means for supporting at least one mirror; a second side; a third side provided with support means for the arm to be supported by the central body; said arm being characterized in that it comprises: at least one stamped sheet shaped to obtain a resistant structure to provide rigidity and bearing capacity by means of a plurality of ribs forming a lattice having a plurality of laminar portions between said ribs. the sheet is galvanized. In the arm of the invention, the sheet can be galvanized. Also, the sheet can have a thickness comprised between 1-2, 5mm. Preferably, the thickness of the sheet can be comprised between l, 2-2mm. In the arm of the invention, the support means of a mirror can be spaced a distance a, and: the first side can have a length comprised between 2, 1-3, 2a; the second side may have a length comprised between 2, 3-3, 4a; the third side may have a length comprised between 0.8-1.2a; the extreme support means may be at a distance comprised between 0-0, 6a of the ends of the first side. Additionally, in the arm of the invention, the adjacent support means of two mirrors can be at a distance comprised between 0.4-0.6a. The support means of the arm of the invention can comprise four mirror seats. On the other hand, in the arm of the invention, the support means can comprise two fixings to the central body configured to allow the arm of the central body to be dismantled, said fixings being able to be located in: a first vertex where the first side and the third converge side; a second vertex where the second side and the third side concur. Optionally, the arm of the invention can further comprise at least one recess in the sheet portion for lightening. Also, in the arm of the invention the first side can be curved-concave to have a shape adapted to the semiparabic shape of the at least one mirror. Likewise, the second side of the arm can be curved-convex to achieve an optimal strength / weight ratio. Also the third side of the arm can be curved-concave, presenting a pronounced concavity for lightening. In the arm of the invention, the plurality of ribs can form a lattice having a lattice selected between triangular, trapezoidal and combinations thereof. A second aspect of the invention relates to a cylinder-parabolic collector support that can comprise at least one arm as described above and a tube-shaped central body formed from a flat plate for: providing torsional rigidity; minimize the number of fixings to the arm; facilitate the assembly / disassembly of the arm. A third aspect of the invention relates to a method for manufacturing an arm according to that described above, said process comprising: a) cutting a development of an arm in a flat sheet to obtain an initial shape; b) embossing the initial shape to form a sturdy structure to provide rigidity and bearing capacity by a plurality of ribs forming a lattice having a plurality of laminar portions between said ribs to obtain a final shape. The procedure may also include: c) punching the final shape to locate the support means. Additionally, the method may also comprise: d) punching the final shape to locate the support means. The manufacturing process of the arms of the invention has the following advantages: - The number of operations necessary to reach the final product starting from the raw material is not highThese operations are also highly automatable, which translates into a lower cost. - The production of this type of parts in series results in higher quality and greater repeatability of the characteristics of the final product, reducing the number of rejects. - When the piece is manufactured with the support points according to the required precision, the need to adjust supports is eliminated, reducing the assembly cost.

BRIEF DESCRIPTION OF THE DRAWINGS The following is a brief description of a series of drawings that help to better understand the invention and that are expressly related to an embodiment of said invention that is presented as a non-limiting example thereof. Figure 1 is a diagram showing a parabolic trough collector. Figure 2 is a side view showing a parabolic trough collector according to the invention. Figure 3 is a view of an arm of the invention where the geometry of the arm is indicated. Figures 4A, 4B and 4C show three alternative designs of an arm according to the invention. Figure 5 is a perspective view of a portion of a manifold showing a plurality of arms that support a plurality of mirrors, said arms being connected to a central body.

Description of a preferred embodiment of the invention In a commercial solar plant, more than 200,000 arms may be required. This huge amount of necessary units, requires that the process by which these elements are manufactured is extremely simple, to reduce costs without losing the capacity of these elements to absorb loads and to provide adequate rigidity and precision. For this reason, the arms that are coupled to the central body 1 of the corbel-like collector, in a direction substantially perpendicular to the focal line 2 of said collector, have a wedge shape having a first side 10 having the support means 11 for supporting the mirrors 3, a second side 20 and a third side 30 having the support means 31 for the arm to be supported by the central body 1. In the invention, the arm is formed from at least one sheet patterned shaped to obtain a sturdy structure to provide stiffness and bearing capacity by a plurality of ribs 42 forming a lattice having a plurality of laminar portions 41 between said ribs 42. These laminar portions may have hollows 43 made to lighten the weight of the arm . The invention also relates to the manufacture of parts from stamped sheet metal. In this process, it starts from a flat sheet of thickness between 1 mm and 2 mm. This sheet is subjected to the action of successive dies or dies that are giving shape to get the final piece has the required consistency. The definitive supports or support means 11 for placing the mirrors 3 can be made on the stamped piece during the manufacturing process. This allows to achieve in the positioning of these housings or support means 11 the precision required for the final lacing of the mirrors 3. Therefore, the fundamental operations comprising the procedure are: - Cut a flat sheet with the appropriate thickness, to obtain a desired initial shape. - Successive stamping / punching operations to form the flat sheet to the desired shape, with a series of ribs or ribs 42 that provide the rigidity and strength required. By means of punching or an equivalent operation it is possible to position the holes or support means 11 that support the mirrors 3 and the support means 31 that tie the arm to the central body 1 of the collector, with sufficient precision so as not to have to carry out additional operations of adjustment. In an embodiment of the invention, the collector design with stamped arms is optimal in terms of performance and cost if a tube formed from welded plate is used as the central body 1. For the arms you can choose sheet thicknesses between 1.2 mm and 2 mm depending on the wind loads that the concrete collector will suffer, due to its position within the field.

Claims (15)

NOVELTY OF THE INVENTION Having described the invention as above, property is claimed as contained in the following: CLAIMS

1. A cylinder-parabolic solar collector support arm configured to be coupled to a central body (1) of the collector as a bracket, in a direction substantially perpendicular to a focal line (2) of the collector, said arm having a wedge shape having: a first side (10) provided with support means (11) to support at least one mirror (3); a second side (20); a third side (30) provided with support means (31) for the arm to be supported by the central body stinking said arm characterized in that it comprises: at least one stamped sheet shaped to obtain a resistant structure to provide rigidity and carrying capacity by means of a plurality of ribs (42) forming a lattice having a plurality of laminar portions (41) between said ribs.

2. The arm of claim 1 characterized in that the sheet is galvanized.

3. The arm of any of claims 1-2 characterized in that the sheet has a thickness comprised between 1-2, 5mm.

4. The arm of any of claim 3 characterized in that the sheet has a thickness comprised between 1.2-2 mm.

5. The arm of any of claims 1-4, characterized in that the support means (11) comprise four mirror seats (3).

6. The arm of any of claims 1-5, characterized in that the support means (31) comprise two fixings to the central body (1) configured to allow the arm to be removed from the central body (1), said fixings being located in: a first vertex where the first side (10) and the third side (30) concur; a second vertex where the second side (20) and the third side (30) concur.

7. The arm of any of claims 1-6 characterized in that it also comprises at least one recess (43) in the sheet portion (41) for lightening.

8. The arm of any of claims 1-7 characterized in that the first side (10) is curved-concave to have a shape adapted to the semi-parabolic shape of the at least one mirror (3).

9. The arm of any of claims 1-8 characterized in that the second side (20) is curved-convex to achieve an optimum strength / weight ratio.

10. The arm of any of claims 1-9 characterized in that the third side (30) is curved-concave presenting a pronounced concavity for lightening.

11. The arm of any of claims 1-10 characterized in that the plurality of ribs (42) form a lattice having a lattice selected between triangular, trapezoidal and combinations thereof.

12. A cylinder-parabolic solar collector support characterized in that it comprises at least one arm according to any of claims 1-11 and a central body (1) in the form of a tube formed from a flat plate for: providing torsional rigidity; minimize the number of fixings to the arm; facilitate the assembly / disassembly of the arm.

13. Process for manufacturing an arm according to claims 1-11, characterized in that it comprises: a) cutting a development of an arm in a flat sheet to obtain an initial shape; b) embossing the initial shape to form a sturdy structure to provide stiffness and bearing capacity by a plurality of ribs (42) forming a lattice having a plurality of laminar portions (41) between said ribs to obtain a final shape.

14. The method of claim 13 characterized in that it further comprises: c) punching the final shape to locate the support means (11).

15. The method of any of claims 13-14 characterized in that it further comprises: punching the final shape to locate the support means (31).