REFLECTIVE DEVICE FOR SOLAR THERMAL POWER PLANT

Abstract

According to one aspect, the present invention relates to a reflection device for solar thermal power plants comprising at least one reflector (2000) comprising at least one solar ray reflecting surface, said at least one reflective surface being curved, characterized in that said at least one reflective surface comprises at least a first part (2010) and a second part (2020) articulated to each other in rotation, the first (2010) and a second part (2020) being configured so that their relative rotation causes a change in the focal area of ​​the reflector (2000).

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of solar power plants and more particularly to Fresnel-type concentrating solar power plants. It also relates to the reflectors used in these power plants. STATE OF THE ART

[0002] In a world where energy is a constant concern, many techniques attempt to extract energy from natural, so-called renewable energy sources such as solar energy.

[0003] One way to produce energy from solar radiation is to convert this radiation into electricity through the photoelectric effect occurring in the heart of photovoltaic cells, whose efficiency is unfortunately still low today.

[0004] A second way to extract energy from solar radiation is to use this light as a heat source. This heat can be harnessed to heat a heat transfer fluid, such as water. Once heated above its boiling point, this liquid can, for example, drive a turbine configured to generate an electric current and thus produce electricity. There are several types of solar power plants, distinguished by their light concentration techniques, heat transfer methods, and thermodynamic conversion techniques. These include parabolic trough solar power plants with linear focal points, central receiver towers, moving-focus parabolic troughs, and linear Fresnel concentrators. All these solar power plants share the common feature of using mirror-like reflectors to concentrate sunlight onto a specific point.

[0005] In Fresnel-type solar thermal power plants, the reflectors form parallel lines, preferably oriented north-south. Their function is to concentrate the incoming solar radiation onto a specific target called the receiver, regardless of the sun's position relative to the target. Therefore, the reflectors must be mobile, and their orientation must change throughout the day to track the sun's path. Each line of reflectors is thus hinged on a single axis of rotation located along the longitudinal axis of the reflectors and oriented along the longitudinal axis of the line of reflectors to achieve a tracking motion that follows the sun's path.

[0006] Reflectors consist of a mirror-like surface designed to reflect sunlight towards the receiver. To maximize the amount of sunlight reflected onto the receiver, the most efficient reflectors have a curved surface. This curvature causes the reflected light rays to converge at a single point, called the focus or focal point, located at a distance from the reflector's center of curvature; this distance is called the focal length. The receiver must then be positioned at this point. In the case of linear Fresnel reflectors, the light rays are concentrated along a line due to the reflectors' linear configuration. US patent 2003 / 0056703 describes such an installation in detail.

[0007] Improving the efficiency of solar power plants is of course an important objective and has been the subject of much research to ensure that the receiver absorbs a maximum of heat and transfers a maximum of heat to the heat transfer fluid.

[0008] These improvements thus relate to the choice of materials for the receiver or its structure. For example, document FR 2458032 describes a receiver structure that improves optical efficiency by eliminating losses in the reconcentrator and thermal bridging losses. The overall efficiency of the solar power plant is therefore increased.

[0009] US patent 2003 / 0056703 describes an alternative solution in which the receiver has a specific structure to improve efficiency. US patent 2009 / 0223510 A1 describes a reflecting device according to the preamble of claim 1.

[0010] Documents DE 28 24 494 A1 and WO 2008 / 157560 A2 describe a reflecting device comprising at least one reflector with a curved reflective surface having at least a first part and a second part articulated to each other in rotation.

[0011] Any solution that further improves the efficiency of a Fresnel-type solar power plant would be highly beneficial.

[0012] The present invention aims to provide a solution to increase the efficiency of a Fresnel-type solar thermal power plant. SUMMARY OF THE INVENTION

[0013] The present invention relates to a reflecting device for solar thermal power plants, comprising at least one reflector, said reflector comprising at least one surface for reflecting solar rays, said reflective surface being curved and having a focal zone, wherein said reflective surface comprises at least a first part and a second part articulated so as to be able to follow the sun's path, and articulated to each other in rotation, the reflecting device comprising a support intended to be fixed to the ground and configured to support the first and second parts, and wherein the first and second parts are each articulated in rotation to the support about the same axis of rotation. The first and second parts are configured such that their relative rotation results in a change in the focal zone of the reflector.

[0014] According to one embodiment, the reflectors are cylindro-parabolic, and therefore have a linear focus, called the focal zone.

[0015] Due to the Earth's movement relative to the sun, the angle of incidence of sunlight changes throughout the day, and the reflectors' tracking of the sun does not allow for a constant focal length. Therefore, if a relatively constant output is desired throughout the day, it is necessary to be able to adjust the focal area of ​​the reflectors, since the receiver is a fixed element of the solar thermal power plant.

[0016] The present invention makes it possible to adjust the focal length of the reflectors of the solar power plant so as to maintain the focal length and therefore the focal area of ​​the reflectors at the level of the receiver.

[0017] This significantly increases the solar power plant's output. Furthermore, this solution proves to be robust and reliable, which is essential in this type of installation to reduce maintenance costs.

[0018] Furthermore, solar power plants are generally installed in relatively dry environments subject to regular winds. Therefore, reflectors must be protected from harsh weather conditions, such as sandstorms, to maintain the reflectivity of the reflective surface.

[0019] Advantageously, the present invention allows, by the relative rotation of the first and second parts, the portions of reflective surface carried by each of the first and second parts to be brought closer together until the reflector closes upon itself. The reflective surface is then protected when necessary. Its lifespan can thus be extended.

[0020] Similarly, it is important to be able to clean the surface of the reflectors efficiently and quickly; here again, the present invention makes it possible to achieve a maximum opening of the reflector so as to be able to easily and efficiently access and clean the reflective surface of the reflectors.

[0021] Finally, reflectors are fragile components and therefore require careful transport and storage. The present invention fulfills this function by allowing the reflector to be closed upon itself by placing the portions of the reflective surface supported by the first and second parts against each other, so that the reflective surface is inaccessible from outside the reflector. The reflective surface is thus protected.

[0022] According to one aspect of the invention, the reflection device according to the present invention comprises a receiver intended to receive at least a part of the radiation reflected by the reflective surface of at least one reflector, said system being configured to adjust the position of the focal area of ​​at least one reflector, by adjusting the relative angular position between at least a first and a second part of said at least one reflector, according to the position of the sun and / or that of the receiver.

[0023] The present invention also relates, in another aspect, to a line of reflectors comprising at least a plurality of reflecting devices according to the present invention comprising at least one reflector, said reflecting devices being aligned along at least one alignment axis parallel to the longitudinal axis of at least one reflector.

[0024] This alignment axis is more or less parallel to the axis formed by the geographic north and south poles in order to optimize exposure to light rays and to allow tracking of the sun during the day by simply rotating the reflecting devices.

[0025] A line of reflectors according to the present invention makes it possible to focus the sun's rays all along the receiver in order to bring more solar energy and thus increase the efficiency of the solar thermal power plant.

[0026] According to another aspect, the present invention relates to a reflector focal length adjustment system for a solar power plant comprising at least one line of reflectors according to the present invention or comprising at least one reflecting device according to the present invention and at least one receiver intended to receive at least a part of the radiation reflected by the at least one reflecting device comprising at least one reflector, said system being configured to adjust the position of the focal area of ​​the at least one reflector, by adjusting the relative angular position between the at least a first and a second part of said at least one reflector, depending on the position of the sun and / or that of the receiver.

[0027] This system then allows for an increase in the efficiency of the solar thermal power plant.

[0028] According to another aspect, the invention relates to a solar field comprising at least one line of reflectors according to the invention and comprising at least one receiver intended to receive at least a part of the radiation reflected by the at least one line of reflectors.

[0029] According to one aspect, the present invention relates to a solar power plant comprising at least one reflecting device according to the present invention and comprising at least one receiver intended to receive at least a part of the radiation reflected by the at least one reflecting device, said system being configured to adjust the position of the focal area of ​​the reflective surface of each reflector, by adjusting the relative angular position between at least a first and a second part of each reflector, depending on the position of the sun and / or that of the receiver.

[0030] Each reflector in a line is configured to be movable in rotation about at least one longitudinal axis and comprising at least two movable parts in relative rotation with respect to each other to adjust the focal length of at least one reflector, and comprising at least one receiver intended to receive at least a part of the radiation reflected by at least one line of reflectors.

[0031] According to one aspect, the present invention relates to a reflecting device comprising at least one reflector and at least one control unit configured to control the relative angular position of at least a first and a second part of at least one reflector as a function of at least one of the following parameters: Geographical location of the solar power plant, Position of the sun; Inclination of the solar rays; Time; Day; Month; Position of the reflecting device relative to a receiver of the solar power plant; Weather conditions; Environmental parameters.

[0032] This reflector configuration control system automates the tracking of the sun's path and also ensures a longer lifespan for the reflectors by positioning them in safe configurations, thanks to the ability to close them. Taking environmental parameters into account further improves the lifespan of the reflector's reflective surface.

[0033] Finally, according to another aspect, the present invention relates to a method for orienting a reflecting device according to any one of claims 1 to 12, the method comprising at least the following step: relative rotation, around the same axis of rotation, of the first and second parts of the reflecting surface of the reflector so as to make the focal zone of the reflector coincide with or approach the position of a receiver in the solar thermal power plant. This adjustment of the focal zone represents a significant gain in the efficiency of the solar thermal power plant. BRIEF DESCRIPTION OF THE FIGURES

[0034] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which: Figures 1a and 1b represent a prior art example of a parabolic Fresnel-type reflector. Figure 2a represents an embodiment of a reflecting device that is not covered by the present invention; Figures 2b to 2d represent two distinct embodiments of the present invention and several possible positionings for one of the two embodiments. Figure 3 represents the prior art of a reflector in a sun-tracking position when the sun is at low incidence, such as in the morning or evening. Figure 4 represents the present invention, according to one embodiment, in a sun-tracking configuration at low incidence and configured to refocus the light rays. Figures 5a to 5g represent several possible configurations of a reflecting device of the present invention according to one embodiment.Figures 6a and 6b show the installation of the present invention at ground level and its cardinal orientation. Figures 7a, 7b and 7c show different modes of motorizing the reflectors according to the possible embodiments of the present invention. Figure 8 shows a field of reflectors according to the present invention and along the longitudinal axis of the receiver.

[0035] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION OF THE INVENTION

[0036] Before going into detail about preferred embodiments, particularly with reference to the figures, we state below various options that the invention may preferentially, but not exclusively, present; these options may be implemented either separately or in any combination thereof: According to the invention, the reflective surface is formed by at least one first part and one second part articulated with respect to each other. This relative articulation of the parts forming the reflective surface enables the "refocusing" function, that is, the modification of the focal area of ​​the reflector. Advantageously, the reflective surface is continuous between the first and second parts. Therefore, there is no intermediate space between the first and second parts other than the clearance necessary for mounting or articulating the first and second parts. In one embodiment, the reflective surface is formed solely by the first and second parts. In another embodiment, only one of the first and second parts is rotationally articulated with respect to the support. This simplifies the structure of the reflector. According to the invention, the reflective surface is curved.Each part has an inner edge facing the inside of the reflector and an outer edge facing the outside of the reflector. Advantageously, the relative mobility of the two parts allows the two outer edges to be brought closer together by rotating the first and second movable parts. This allows, for example, the reflector to be folded back on itself to protect its reflective surface or to facilitate its transport or storage. According to the invention, the reflecting device comprises a support intended to be fixed relative to the ground and configured to support a first and a second part, and the first and second parts are each articulated for rotation relative to the support.

[0037] This ensures that the reflecting device remains fixed. According to the invention, the first part and the second part are each articulated for rotation relative to the support around the same axis of rotation. This allows for a "refocusing" function, that is, an adjustment of the position of the focal zone of the reflecting device. Advantageously, at least one reflector extends primarily along a longitudinal axis, and said axis of rotation is parallel to said longitudinal axis.

[0038] This allows for simplified tracking of the sun's path. Advantageously, at least one reflector extends mainly along a longitudinal axis and the first and second axes of rotation are parallel to the longitudinal axis of the reflecting device.

[0039] This allows for simplified tracking of the sun's path. Advantageously, the tangents to each of the surface portions carried by the first and second parts, taken at the respective axes of rotation of the first and second parts, form an angle α. The reflecting device is configured to allow the angle α to vary between 0° and 300°, advantageously between 0° and 180°, and preferably between 160° and 180°. Advantageously, at least one reflector is configured to allow a so-called cleaning configuration in which the angle α is greater than or equal to 180°, and preferably greater than 270° and preferably greater than 300°. In this configuration, the angle α is at its maximum. Access to the first and second parts is facilitated to simplify cleaning or maintenance.Furthermore, in this position, a cleaning liquid or rainwater flows easily by gravity off the reflective surface without stagnating and therefore without causing residue deposits on it. Advantageously, at least one reflector is configured to allow a so-called cleaning configuration in which the angle α is less than or equal to 340°.

[0040] In this configuration, the angle α is maximized, allowing the use of suitable and specific cleaning devices. Access to the first and second parts is thus facilitated, simplifying cleaning and maintenance. Advantageously, at least one reflector is configured to allow a so-called folding configuration in which the angle α is less than 40°, and preferably less than 20°, preferably less than 10°, and preferably equal to 0°. This allows the reflective surface to be folded back on itself for protection. Advantageously, this configuration protects the reflector's reflective surface from weather conditions that could damage it.Advantageously, the folding configuration includes at least two positions: a head-up position, corresponding to a position where the reflective surface of at least one reflector is mostly above the axis or axes around which the first and second parts rotate (therefore above the longitudinal axis), and a head-down position, corresponding to a position where the reflective surface of at least one reflector is mostly below the axis or axes around which the first and second parts rotate (therefore below above the longitudinal axis).

[0041] The head-up position can be used in the case of passing bad weather and / or in the case of replacing or installing reflectors.

[0042] The upside-down position provides increased protection for the reflector, particularly its reflective surface, during prolonged and severe weather. Furthermore, this position ensures simple and secure storage of the reflector. Advantageously, the folding configuration allows for at least one other position in which the first and second parts are oriented in the direction of a prevailing wind. Typically, the first and second parts are oriented horizontally. In one embodiment, the first and second parts are hinged so that they fold onto one another. The reflector is then in a so-called folding configuration. In this configuration, the reflective surface portions carried by each of the first and second parts face each other or are oriented towards one another. The ends of the first and second parts, when folded onto each other, are in contact or separated by a distance d1. In one embodiment, d1 is zero or less than 0.7 times, and preferably 0.5 times and preferably 0.2 times, the distance separating one end from its axis of rotation.According to another embodiment, d1 is zero or less than 1 meter, and preferably 0.5 meters and preferably 0.2 meters. In one embodiment, the folding configuration comprises at least two positions: an upright position, corresponding to a position where the reflective surface of at least one reflector is predominantly above the axis or axes around which the first and second parts rotate, and an inverted position, corresponding to a position where the reflective surface of at least one reflector is predominantly below the axis or axes around which the first and second parts rotate. In one embodiment, the first and second parts each have a rear face opposite the reflective surface. The first and second parts are hinged so that their rear faces face each other or are turned towards each other in a so-called cleaning configuration.In the so-called cleaning configuration, the ends of the first and second parts are either in contact or separated by a distance d2. In one embodiment, d2 is zero or less than 0.7 times, and preferably 0.5 times and preferably 0.2 times, the distance separating an end from its axis of rotation. In another embodiment, d2 is zero or less than 1 meter, and preferably 0.5 meters. Advantageously, at least one actuator, also referred to as the actuator, is configured to drive the first and second parts, articulated with respect to each other, in relative rotation.

[0043] This enables a "refocusing" function, meaning an adjustment of the focal point of the reflecting device. Using a single motor reduces potential mechanical problems. Advantageously, at least one actuator is configured to drive the first and second parts in relative rotation via at least one common drive shaft driving the first articulated part and the second articulated part in rotation.

[0044] This results in the technical effect of allowing for an angular offset between at least one first and second articulated section, both mounted on the same drive shaft. This enables precise control of the reflector's focal point while minimizing installation complexity and cost. Advantageously, the reflecting device includes at least one transmission device coupled on one side to at least one common drive shaft and coupled on the other side to one of the first and second parts such that the rotational speed of the first and second parts is different. Advantageously, the reflecting device includes at least one transmission device coupled on one side to at least one common drive shaft and coupled on the other side to one of the first and second parts, the transmission device being configured such that when the drive shaft rotates, the part of the first and second parts coupled to the transmission device rotates at a different speed than the other part of the first and second parts.

[0045] This results in the technical effect that, for the same rotational time of the drive shaft, one of the two parts rotates through a greater angle than the other. Thus, an angular offset can be achieved between at least one first and second articulated part, both mounted on the same drive shaft. This allows, for example, precise control of the reflector's focal point while limiting the complexity and cost of the installation. The two parts can also be folded over each other so that the reflective surface area of ​​one of the first and second parts is aligned with the reflective surface area of ​​the other. Advantageously, at least two actuators, each coupled to one of the first and second parts and configured to drive the first and second parts in relative rotation.

[0046] This results in the technical effect of allowing for an angular offset between at least one first and second articulated section. This enables precise control of the reflector's focal point while limiting the complexity and cost of the installation. Furthermore, the actuators used can be of lower power than in the case of a single actuator. Advantageously, at least one individual radius of curvature of at least one first articulated part is identical to at least one individual radius of curvature of at least one second part. Advantageously, at least one individual radius of curvature of at least one first articulated part is different from at least one individual radius of curvature of at least one second part. Advantageously, at least one reflective surface comprising at least one first and one second articulated part has at least one parabolic shape and preferably forms a single parabola. Advantageously, the parabolic shape includes an opening of between 0.5 m and 2 m, advantageously between 0.75 m and 1.5 m, and preferably equal to 1 m.Advantageously, the reflecting device includes a control unit configured to control the relative angular position of at least a first and a second part as a function of at least one of the following parameters: Geographic location of the solar power plant; Position of the sun; Inclination of the solar rays; Time; Day; Month; Position of the reflecting device relative to a receiver of the solar power plant; Weather conditions; Environmental parameters; Advantageously, at least one alignment axis is parallel to the geographic North / South axis.

[0047] This allows us to follow the sun's path during the day simply by rotating the reflecting device around this alignment axis. Advantageously, at least one drive shaft is configured to rotate at least one reflector, said at least one rotation being generated by at least one actuator.

[0048] This allows us to follow the sun's path throughout the day. Advantageously, each reflector includes at least one transmission device, said at least one transmission device being configured to achieve an angular offset between at least a first and a second part of each reflector.

[0049] This allows the focal area position of each reflector to be adjusted individually, meaning that each reflector can be controlled independently of the others in order, for example, to perform maintenance on one reflector without disrupting the operation of the others. Advantageously, at least one first drive shaft is configured to rotate at least one first part of each reflector and wherein at least one second drive shaft is configured to rotate at least one second part of each reflector.

[0050] The use of two drive shafts allows for very good synchronization between all the reflectors of their movement. Advantageously, at least one transmission device is configured to achieve an angular offset between at least one first and second drive shaft of the transmission.

[0051] This reduces the number of transmission devices and therefore reduces maintenance work by simplifying the reflector line infrastructure. Advantageously, at least one first drive shaft of transmission is configured to cooperate with at least one first actuator and in which at least one second drive shaft of transmission is configured to cooperate with at least one second actuator.

[0052] The use of two actuators makes it possible to reduce their power and to be able to control one part of the reflector independently of the other, further simplifying the infrastructure of the line of reflectors. Advantageously, the reflecting device comprises a plurality of reflectors aligned to form a line of reflectors, each reflector extending principally along a longitudinal axis and the line of reflectors extending along said longitudinal axis.

[0053] Aligning the reflectors along the same axis as the line of reflectors allows for simplified control of the reflectors to follow the sun's path. Advantageously, said longitudinal axis is parallel to the Earth's geographic North / South axis. Tracking the sun's path is simplified by this orientation. Advantageously, the reflecting device comprises at least one drive shaft, preferably a single drive shaft, coupled to an actuator, preferably a single actuator, the drive shaft being configured to rotate said first and second parts of the reflector line.

[0054] This allows for a simplification of the reflector line infrastructure and a reduction in maintenance time since the mechanical parts are fewer in number. Advantageously, the reflecting device comprises a single drive shaft for the line of reflectors and includes, for each reflector in the line of reflectors, at least one transmission device coupled on one side to the single drive shaft and on the other side to one of the first and second parts of the reflector. The transmission device is configured such that when the drive shaft rotates, the part of the first and second parts coupled to the transmission device rotates at a different speed than the other part of the first and second parts.

[0055] This allows for an angular separation between each of the first and second parts, and thus for adjusting the focal area of ​​each reflector independently of the other reflectors.

[0056] This also allows for cleaning or maintenance operations to be carried out on a specific reflector in the reflector line without having to reconfigure all reflectors in the same way. As a result, the solar power plant's efficiency is minimally impacted. Advantageously, the reflecting device includes at least one first drive shaft configured to rotate at least one first part of each reflector in the line of reflectors and includes at least one second drive shaft, different from the first drive shaft, configured to rotate at least one second part of each reflector in the line of reflectors.

[0057] This allows each part of the reflector to be acted on independently, but to have synchronicity between each reflector. Advantageously, the reflecting device includes an actuator configured to drive both the first and second drive shafts in rotation. The reflecting device includes at least one transmission device coupled to the actuator and to at least one of the first and second drive shafts, the transmission device being configured so that the first and second drive shafts can rotate at different speeds when the actuator operates to vary the angle separating the first and second parts of each reflector.

[0058] Thus, a transmission device common to a line of reflectors is configured to vary the angle separating the first and second parts of each reflector. Advantageously, the reflecting device includes a first actuator configured to drive in rotation at least one first drive shaft and includes a second actuator, different from the first actuator, configured to drive in rotation at least one second drive shaft. Advantageously, the reflecting device includes at least one control unit, configured to drive at least one actuator so as to control the relative angular position of the first and second parts of each reflector.

[0059] This allows the reflector configuration to be modified to adapt it to the needs of the solar power plant. Advantageously, the reflecting device includes a receiver intended to receive at least a part of the radiation reflected by the reflective surface of at least one reflector, said system being configured to adjust the position of the focal area of ​​at least one reflector, by adjusting the relative angular position between at least a first and a second part of said at least one reflector, according to the position of the sun and / or that of the receiver.

[0060] This allows for an improvement in the efficiency of the solar power plant. Advantageously, the first and second parts of the reflector are both located only on one side or the other of the receiver with respect to the vertical line passing through the receiver. For example, the first and second parts can both be located entirely to the right of the receiver, or conversely, both can be located entirely to its left. Advantageously, the reflector is configured to be located only on one side or the other of the receiver with respect to the vertical line passing through the receiver. Advantageously, the reflector is configured to be located entirely on one side or the other of the receiver with respect to the vertical line passing through the receiver. Advantageously, at least one control unit is configured to control at least one actuator.

[0061] This control unit allows the management of an entire line of reflectors in order to follow the sun's path but also to intervene according to maintenance and weather conditions. The device includes a support intended to be fixed relative to the ground and configured to support the first and second parts, the first and second parts each being articulated in rotation relative to the support.

[0062] This rotation of the first and second parts allows us to follow the sun's path during the day. Advantageously, at least one actuator is configured to drive the first and second articulated parts in relative rotation with respect to each other.

[0063] This relative rotation allows adjustment of the focal area of ​​the reflector. Advantageously, at least two actuators, coupled respectively to one of the first and second parts and configured to drive the first and second parts in relative rotation.

[0064] Using at least two actuators allows the first part to be controlled independently of the second and vice versa. Advantageously, the tangents to each of the surface portions carried by the first and second parts, taken at the level of the respective axes of rotation of the first and second parts, form an angle α between them. The reflection device is configured to allow an evolution of the angle α between 60° and 160°, advantageously between 45° and 180° and preferably between 10° and 300°.

[0065] Varying this angle allows the reflectors to be configured in various advantageous positions. Advantageously, the folding configuration includes at least two positions: a head-up position, corresponding to a position where the reflective surface of at least one reflector is mostly above the axis or axes around which the first and second parts rotate, and a head-down position, corresponding to a position where the reflective surface of at least one reflector is mostly below the axis or axes around which the first and second parts rotate.

[0066] This folding position helps to protect the reflective surface of the reflectors. Advantageously, the at least first and second parts each comprise at least one radius of curvature, called the individual radius of curvature, said individual radii of curvature being between 10m and 100m, advantageously between 15m and 50m and preferably equal to 20m. Advantageously, the at least one reflective surface composed of the at least first and second parts comprises at least one radius of curvature, called the overall radius of curvature, being between 10m and 100m, advantageously between 15m and 50m, and preferably equal to 20m. Advantageously, said longitudinal axis is parallel to the North / South geographic axis.

[0067] This allows the sun's path to be tracked by rotating the reflectors around their longitudinal axis. Advantageously, the reflecting device includes a single drive shaft for the line of reflectors and includes for each reflector in the line of reflectors at least one transmission device coupled on one side to the single drive shaft and coupled on the other side to one of the first and second parts of the reflector, the transmission device being configured so that when the drive shaft rotates, the one of the first and second parts coupled to the transmission device rotates at a different speed from the other of the first and second parts.

[0068] It is specified that, within the framework of the present invention, the terms "Fresnel concentrator," "Fresnel reflector," "reflector," or their equivalents are defined as a device comprising a surface capable of reflecting sunlight and focusing it onto a point called the focal point of the reflector. Furthermore, these reflectors have a greater extent along an axis called the longitudinal axis of the reflector, or alignment axis. Similarly, these reflectors have an axis called the vertical axis of the reflector, which is perpendicular to the longitudinal axis and runs vertically.

[0069] It is specified that within the framework of the present invention, the term "solar axis of the reflector" or its equivalents are defined as an axis passing through the center of the sun and through the longitudinal axis of the reflector in an orthogonal manner.

[0070] It is specified that, within the framework of the present invention, the term "focal zone" or its equivalents are defined as a zone of convergence of the light rays reflected by said reflector. In the case of a reflector that extends along a longitudinal direction, typically a parabolic-cylindrical reflector, this focal zone extends primarily along the longitudinal direction of the parabolic-cylindrical reflector.

[0071] In the figures illustrating non-limiting examples, the parabolic-cylindrical reflector extends mainly in the horizontal direction and the focal area then extends mainly in the horizontal direction.

[0072] If we consider a vertical section of the reflector, then the focal area is limited to a point corresponding to the focal point of this section.

[0073] It is specified that within the framework of the present invention, the term "central axis of the reflector" or its equivalents are defined as an axis passing through the longitudinal axis of the reflector and being perpendicular to its reflective surface.

[0074] It is specified that, within the scope of the present invention, the term "individual radius of curvature" or its equivalents is defined as the radius of curvature of each of the at least one first and second mutually articulated parts. It is further specified that, within the scope of the present invention, the term "overall radius of curvature" or its equivalents is defined as the radius of curvature of the reflecting surface of the reflector, said reflecting surface comprising at least one first part and one second part.

[0075] It is specified that within the framework of the present invention, the term "opening of a parabola" or its equivalents are defined as the distance separating the two ends of the parabola.

[0076] It is specified that within the framework of the present invention, the term "solar field" or its equivalents are defined as a space comprising a plurality of lines of reflectors and a receiver.

[0077] It is specified that, within the framework of the present invention, the term "North / South axis" or its equivalents are defined as an axis passing substantially through the Earth's geographic North Pole and the Earth's geographic South Pole. Similarly, the term "East / West axis" or its equivalents are defined as an axis perpendicular to an axis passing through the Earth's geographic North Pole and the Earth's geographic South Pole.

[0078] The present invention relates to improving the efficiency of a solar thermal power plant, and more particularly of a solar thermal power plant with Fresnel reflectors. A solar thermal power plant comprises at least one solar array. Figure 8 shows a view along the North / South axis of a solar array 6000 according to the present invention. The solar array comprises at least one line of reflectors 2000 and a single receiver 3000 capable of receiving solar energy and converting this energy by heat transfer with a heat transfer fluid, for example. To achieve this, the solar rays 4, 5 must be concentrated as much as possible onto this receiver 3000. That is to say, the reflectors 2000 must focus the solar rays 4, 5 at the level of the receiver 3000. To do this, the focal zone 3 of the reflectors 2000 must correspond to the position of the receiver 3000.

[0079] As the sun follows a very precise path in the sky, the 2000 reflectors must be reoriented throughout the day to follow the sun and thus always have the maximum amount of sunlight on their reflective surface.

[0080] The sun's path across the sky changes the angle of incidence of the sun's rays 4 with the horizon, which in turn changes the focal area 3 of the reflectors 2000 when they follow the sun.

[0081] The prior art illustrated by figures 1a and 1b representing a reflector 100, only allows tracking of the sun during the day without adjustment of the focal length of the reflectors, thus reducing the energy input received by the receiver, thereby reducing the efficiency of the solar thermal power plant.

[0082] Sun tracking is possible by rotating the reflectors around their longitudinal axis. This longitudinal axis is more or less collinear with the geographic North / South axis. Therefore, rotating around this axis allows the sun to be tracked throughout the day.

[0083] This reflector 100 comprises a reflective surface curved in a parabolic shape, referred to as a parabola in the following text. This parabola includes a central axis 101. This reflector 100 is rotatable, producing an angular deviation between the central axis 101 and the vertical axis 1. This rotational movement allows tracking of the sun's path throughout the day. This movement is illustrated in Figure 1b. This reflector 100 has a fixed radius of curvature, meaning that the aperture of the parabola 2 is constant. Consequently, during the day, when the sun's rays strike at a shallow angle, the focal length of the reflector 100 is unintentionally altered and no longer corresponds to the distance between the reflector 100 and the receiver 3000.

[0084] This focal length and therefore the focal area is a function of the aperture of the parabola 2. Since this aperture is fixed, the focal length of the reflector is therefore only a function of the angular deviation between the solar axis of the reflector 100 and its vertical axis 1.

[0085] Figure 3 illustrates this situation precisely. The prior art reflector 100 is rotated to track the sun's path. Since the sun is low in the sky, meaning the sun's rays strike the horizon at a shallow angle, the focal point of reflector 100 no longer corresponds to the position of receiver 3000. Consequently, a significant amount of solar energy is lost. Rotating reflector 100 around its longitudinal axis ensures maximum sunlight exposure on its reflective surface; however, the defocusing caused by this rotation reduces the efficiency of the solar thermal power plant.

[0086] The present invention proposes, among other things, a reflection device comprising a reflector whose reflective surface comprises at least a first part and a second part whose relative angular positions are modifiable.

[0087] Each of these parts is rotatable relative to the other and to the longitudinal axis of the reflector, enabling it to track the sun's path. Each of the first and second parts is therefore rotationally articulated relative to a support 2050 of the reflector. Thus, the present invention retains the advantages of sun tracking in terms of sunlight illumination and solves the problem of defocusing by allowing control of the reflector's focal length.

[0088] Figure 2a shows a reflector 1000, which is not covered by the present invention, comprising a reflective surface and including at least a first part 1010 and at least a second part 1020. Each of these parts includes its own axis of rotation 1011, 1021. Each of the at least two parts 1010 and 1020 of the reflector 1000 is rotatable about its own axis of rotation 1011 and 1021, these axes being parallel to the longitudinal axis of the reflector 1000 in order to track the sun. Thus, by tracking the sun's path during the day by applying a rotation to each of the two parts 1010 and 1020, it is possible to adjust the position of the focal zone 3 of the reflector 1000 so that it corresponds to the position of the receiver 3000.

[0089] According to a particularly advantageous embodiment illustrated by Figure 2b, the reflector 2000 comprises a reflective surface including at least a first part 2010 and at least a second part 2020. These two parts are hinged in rotation to each other about the same axis, which is preferably the longitudinal axis 2030 of the reflector 2000. A simultaneous and / or consecutive rotation of the first and second parts 2010 and 2020 around this longitudinal axis 2030 also allows the reflector 2000 to follow the path of the sun.

[0090] Figure 2c represents, according to one embodiment, the reflector 2000 adjusted in rotation about its longitudinal axis 2030 and whose focal length is adjusted by relative rotation of the two parts 2010 and 2020 of the reflecting surface about the central axis 2001 of the reflector 2000. The opening of the parabola is therefore adapted so that the focal length coincides with the receiver 3000.

[0091] Figure 2d shows the configuration of reflector 2000, according to one embodiment, when the sun's rays have a low angle of incidence. The aperture of the parabolic dish is reduced to adjust the focal length, which is then reduced so that the focal zone 3 of reflector 2000 coincides with receiver 3000.

[0092] According to the present invention, the tangents to each of the surface portions carried by the first and second parts 2010 and 2020, taken at the level of their respective axes of rotation, form an angle α between them.

[0093] Figure 4 illustrates the present invention according to one embodiment. The relative rotation adjustment of parts 2010 and 2020 of the reflector 2000 makes it possible to position the focal zone 3 of the reflector 2000 in the same place as the receiver 3000, so as to optimize the thermal energy at the receiver 3000 compared to Figure 3 representing the same situation according to the prior art.

[0094] This positioning of the reflector 2000, as well as the adjustment of the position of the focal zone 3 of the reflector 2000, are ensured, according to an embodiment of the present invention, by a control unit 4000 of the reflector 2000.

[0095] Advantageously, this 4000 piloting unit includes means for piloting and controlling the angular position of each of the first and second parts 2010 and 2020 around the longitudinal axis 2030 of the reflector 2000.

[0096] The control of the configuration of reflector 2000, that is to say the angular position of the central axis of reflector 2001 and the opening of the parabola, is controlled by the control unit 4000 according to at least one parameter among: wind direction, wind force, position of the sun, date, time, year, weather forecasts, humidity of the environment of reflectors 2000, hail detection, doppler data of location of rain, snow, hail clouds, and more generally all environmental data that may affect the performance of the solar power plant.

[0097] Figures 5a to 5g illustrate, according to one embodiment, the different configurations that reflector 2000 can take and more particularly the articulated parts 2010 and 2020 of reflector 2000 during the day and / or according to its operations.

[0098] Thus, according to one embodiment, Figure 5a shows the configuration of reflector 2000 when it is in cleaning and / or maintenance mode. The reflectors of a solar thermal power plant must remain clean so that their reflective surface has the highest possible solar ray reflection coefficient in order to optimize the solar energy reflected by the reflectors. Since the reflectors are exposed to the solar thermal power plant environment all day long, their reflective surface must be cleaned regularly. This procedure is extremely difficult according to prior art because the fixed aperture of the parabolic dish makes accessing the reflective surface, which can be quite large, difficult. Therefore, expensive and complex robotic equipment is required when the reflective surfaces are curved.Furthermore, the invention ensures that, in this configuration, the cleaning liquid, or any other fluid, does not remain trapped in the hollow of the reflector 2000 but flows out by gravity. Indeed, according to the configuration of prior art reflectors, the center of the parabola formed by the reflector is a place where residue accumulates during cleaning, for example. The evaporation of the fluid then leaves behind a layer of dry residue that significantly degrades the reflectivity of the reflective surface at the center of the parabola.

[0099] According to the present invention, the opening of the parabola is adjustable; thus, in cleaning mode and according to one embodiment, it is maximized to allow access to the entire reflector 2000. This configuration is at least partially characterized by a minimized distance 2002 between the two ends of the parabola formed by the reflector 2000. These two ends are located vertically below the respective axis of rotation 2030 of the first and second parts 2010 and 2020.

[0100] For example, in this cleaning configuration, the 2002 distance is less than the 2004 distance, corresponding to the maximum opening of the parabola, advantageously at 2 times the 2004 distance and preferably at 5 times the 2004 distance.

[0101] According to this embodiment, at least one first part 2010 of the reflector 2000 has a maximum relative rotation about the longitudinal axis 2030 of the reflector 2000 with respect to at least one part 2020. According to another embodiment, at least one second articulated part 2020 of the reflector 2000 has a maximum relative rotation about the longitudinal axis 2030 of the reflector 2000 with respect to at least one part 2010. According to a third embodiment, the at least one first part 2010 and a second part 2020, mutually articulated, have a maximum rotation relative to each other about the longitudinal axis 2030 of the reflector 2000 so as to allow easy access to the reflective surface of the reflector 2000 for any maintenance operations on said reflective surface.These maintenance operations may consist of inspecting the condition of the reflector's reflective surface, cleaning it and replacing it if necessary.

[0102] Typically, in this cleaning configuration, the angle α, referenced as α2002, is greater than 180° and preferably greater than 270° and preferably greater than 300°.

[0103] According to a preferred embodiment, the angle α2002 corresponds to the maximum angle that the reflector can take.

[0104] According to one embodiment, Figure 5b illustrates reflector 2000 in a reflective configuration, for example, in the morning. Since the sun's rays are low on the horizon, reflector 2000 is first rotated about its longitudinal axis 2030 in order to collect the maximum amount of sunlight. This also changes its focal length; therefore, the aperture of reflector 2000's parabolic dish must be reduced to decrease its focal length and make the focal zone 3 of reflector 2000 coincide with receiver 3000. To achieve this, at least a first and a second mutually articulated part 2010 and 2020 are adjusted in relative rotation to reduce the aperture of reflector 2003's parabolic dish and thus reduce the focal length of reflector 2000.This rotation around the longitudinal axis 2030 of the reflector 2000 and the adjustment of its focal length ensures an improvement in the energy received by the receiver 3000 and thus allows an improvement in the efficiency of the solar thermal power plant.

[0105] Typically, in this configuration, the angle α, referenced as α2003, is between 20° and 240°, advantageously between 60° and 180°

[0106] According to one embodiment, the adjustment of the focal area is carried out by a correction of the angle α between 0° and 10°, advantageously between 0.1° and 8° and preferably between 0.5° and 4°.

[0107] According to one embodiment, these variations are carried out relative to an angle α equal to 180°.

[0108] In one embodiment, Figure 5c shows the configuration of reflector 2000 when the sun is high in the sky, such as at midday. The aperture of parabolic dish 2003 is therefore important to increase the focal length, allowing the focal zone 3 of reflector 2000 to coincide with receiver 3000. The orientation of reflector 2000 along its longitudinal axis 2030, which is substantially aligned with the North / South geographic axis, also ensures the overlap of focal zone 3 of reflector 2000 with receiver 3000, as well as maximum irradiance of the reflecting surface of reflector 2000.

[0109] Typically, in this configuration, the angle α, referenced as α2004, is between 20° and 240°, advantageously between 60° and 180°. The angle α2004 is advantageously greater than the angle α2003, and the distance 2004 is advantageously greater than the distance 2003.

[0110] The positions of reflector 2000 illustrated by figures 5b and 5d correspond to an example of reflector position when the sun is low in the sky, such as in the morning and afternoon.

[0111] According to one embodiment, Figure 5d illustrates the configuration of reflector 2000 in the afternoon, for example, when the sun's rays have a lower angle of incidence than at midday. Similar to Figure 5b, the radius of curvature of reflector 2000, formed by at least one mutually articulated first and second part, is adjusted so that the focal area of ​​reflector 2000 coincides with receiver 3000.

[0112] Typically, in this configuration, the angle α, referenced as α2003, is between 20° and 240°, advantageously between 60° and 180°

[0113] Solar thermal power plants are generally located in areas with high levels of sunshine, leading to aridity or even drought in the surrounding environment. The spatial extent of a solar thermal power plant is quite significant, as it can encompass several dozen solar fields. A solar field includes at least one 3000W receiver in the form of a linear conduit, preferably oriented along a north-south axis, and a series of reflectors arranged to direct the reflected solar energy to the receiver.

[0114] Furthermore, a solar field is easily subjected to climatic variations in terms of temperature, pressure, rainfall, and wind. Wind blowing in an unprotected, dry location generally results in sandstorms. Wind-borne sand can cause significant degradation of the reflector's reflective surface. To prevent this type of damage, as well as damage caused during the handling, storage, and / or transport of the reflectors, the present invention proposes, according to one embodiment, a retracted configuration known as a reflector protection system.

[0115] Figures 5e, 5f and 5g illustrate an embodiment of the present invention in configurations for protecting the reflective surface of reflector 2000.

[0116] Figure 5e illustrates more particularly a configuration corresponding to the opening of the smallest parabola 2005, that is to say to a positioning of at least one first articulated part 2010 and at least one second articulated part 2020 as close as possible to each other by the application of a relative rotation around the longitudinal axis 2030 of the reflector 2000.

[0117] In this configuration, the portions of reflective surface carried respectively by the first and second parts are brought together so as to be positioned opposite each other.

[0118] Advantageously, the end of each of the first and second parts 2010 and 2020 includes a joint so that the ends of the first and second parts 2010 and 2020 can come into contact with each other so as to close the reflector and thus protect its reflective surface.

[0119] Preferably the 2005 distance is smaller than the 2003 distance, advantageously twice as small and preferably five times smaller.

[0120] Typically, in this configuration, the angle α, referenced α2005, is less than the angle α2003, and the distance 2005 is less than the distance 2003. Advantageously, the angle α2005 is less than 40° and preferably less than 20° and preferably less than 10° and preferably equal to 0°.

[0121] According to an embodiment illustrated by figures 5f and 5g, this configuration of the closed reflector 2000, called the folding configuration, can be made at any angle around the longitudinal axis 2030 of the reflector 2000.

[0122] This folding configuration allows the reflective surface of reflector 2000 to be protected according to environmental conditions. For example, in the event of strong winds blowing from east to west, it may be advantageous to position reflector 2000 according to the configuration shown in Figure 5f in order to reduce its wind resistance.

[0123] Similarly, Figure 5g illustrates a situation involving falling rain and / or hail; the reflector 2000, positioned as such, is protected from damage that this weather could cause. In this configuration, the outer edges of the first and second parts, 2010 and 2020, are brought to their lowest position in the same direction of rotation in order to preserve the reflective surface of reflector 2000.

[0124] Figures 6a and 6b illustrate the on-site installation of an example of a reflector 2000 according to the invention. This installation takes place on a surface 5000, preferably previously leveled. The reflector 2000 is preferably mounted on at least one support 2050 by means of a bracket 2040. The bracket supports the pivot joint allowing the rotation of at least one part 2010, 2020. Advantageously, this at least one support 2050 can be at least one pillar. This at least one support pillar 2050 ensures the stability of the reflector 2000 when it rotates about its longitudinal axis 2030.

[0125] Advantageously, and according to one embodiment, the reflector 2000 can be held by at least two supports 2050. Each support 2040 carries a pivot joint. For example, as illustrated, this support 2040 forms a bearing 2035 for guiding the rotation of at least one of the first and second parts.

[0126] According to one embodiment, Figure 6a illustrates a reflector 2000 along its longitudinal axis 2030, while Figure 6b illustrates the same reflector 2000 along an axis perpendicular to its longitudinal axis 2030.

[0127] Advantageously, the longitudinal axis 2030 of the reflector 2000 is collinear with the North / South geographic axis.

[0128] According to one embodiment, during the day, the reflector 2000 performs a rotation of each of the first and second mutually articulated parts 2010 and 2020 around its longitudinal axis 2030 collinear with the North / South geographical axis and in the East to West direction so as to follow the path of the sun in the sky.

[0129] During the day, in parallel with this tracking of the sun, the relative rotation of at least one first articulated part 2010 and at least one second articulated part 2020 allows an adjustment of the focal length of the reflector 2000 and more particularly a superposition of the focal area 3 of the reflector 2000 with the receiver 3000.

[0130] Figures 7a to 7b illustrate several embodiments of the motorization of a line of 2000 reflectors according to the present invention.

[0131] According to an embodiment illustrated in Figure 7a, a single actuator 4200 drives a single transmission shaft 4100. This actuator 4200 is controlled by the control unit 4000. For each reflector, a transmission device 4110, for example a gearbox, is associated with one of the first and second sections. The control unit 4000 ensures the control of each transmission device 4110 so as to achieve identical and / or non-identical rotation of each of the mutually articulated first and second sections of each reflector 2000 comprising the line of reflectors.

[0132] Advantageously, the 4100 transmission drive shaft includes a number of 4110 transmission devices at least equal to the number of 2000 reflectors.

[0133] Preferably, each 2000 reflector includes at least one 4110 transmission device.

[0134] Advantageously, the transmission device 4110 ensures an angular offset between at least one first articulated part (2010a, 2010b, 2010c, 2010d) of the reflector and at least one second articulated part (2020a, 2020b, 2020c, 2020d) of the reflector.

[0135] For each reflector, the common shaft 4100 drives one of the first and second parts as well as the transmission device 4110. The latter drives in rotation the other of the first and second parts.

[0136] Starting from the rotational speed of the common shaft 4100, the first and second parts can rotate at different speeds. For the same rotational time, the first and second parts can then rotate through different angles, the faster-rotating part having traversed a larger angular sector. This results in a relative rotation of the first and second parts.

[0137] In an extreme case, it can be foreseen that the transmission device decouples one of the first and second parts so that only the other part is driven in rotation by the common shaft 4100.

[0138] Advantageously, the control unit described above controls the transmission device as well as the rotational speed or number of rotations of the common shaft.

[0139] According to one embodiment, the transmission device 4110 can be a transmission box. This transmission device 4110 allows for a reduced angular offset to perform the "refocusing" function, that is, the adjustment of the position of the focal zone of the reflector.

[0140] According to another embodiment, the transmission device 4110 allows for a large angular offset between each of the first and second mutually articulated parts to perform on the one hand the "refocusing" function and on the other hand the movements necessary to obtain positions favorable to retraction and maintenance operations.

[0141] The use of a transmission device specific to each reflector allows maintenance of one reflector without modifying the configuration of the other reflectors.

[0142] In one embodiment, each reflector can be configured independently of the other reflectors. Any maintenance operation on a reflector does not result in a complete shutdown of the reflector line.

[0143] Furthermore, this embodiment allows the focal length of each reflector in the same line of reflectors to be adjusted independently.

[0144] According to an embodiment illustrated in Figure 7b, a single actuator 4200 drives at least two drive shafts 4120 and 4130. Here again, a control unit 4000 provides control and guidance for the reflector line. The actuator 4200 drives at least two drive shafts 4120 and 4130 via at least one transmission device 4110.

[0145] Said at least one transmission device 4110 ensures a different and variable angular offset and / or rotational speed between the transmission drive shaft 4120 and the transmission drive shaft 4130. The two transmission drive shafts 4120 and 4130 are interdependent.

[0146] According to one embodiment, the transmission drive shaft 4130 drives in rotation at least one first articulated part (2010a, 2010b, 2010c, 2010d) of the reflector, and the transmission drive shaft 4120 drives in rotation at least one second articulated part (2020a, 2020b, 2020c, 2020d) of the reflector.

[0147] This embodiment allows for a very high degree of synchronization in the movements of the reflectors. Furthermore, the use of a single 4110 transmission device ensures a reduction in the number of potential failures and a simplification of the reflector line infrastructure, as the number of 4110 transmission devices is reduced.

[0148] According to an embodiment illustrated by Figure 7c, at least one actuator 4210 drives a transmission drive shaft 4120 in rotation and at least one actuator 4220, different from the actuator 4210, drives a transmission drive shaft 4130 in rotation.

[0149] According to one embodiment, each actuator 4210 and 4220 is controlled by a separate control unit 4010, 4020.

[0150] According to another embodiment not shown, a single control unit manages the different actuators 4210 and 4220 of the same reflector or line of reflectors.

[0151] According to one embodiment, the transmission drive shaft 4130 drives in rotation at least a first articulated part (2010a, 2010b, 2010c, 2010d) of each reflector in the line of reflectors.

[0152] According to one embodiment, the transmission drive shaft 4120 drives in rotation for each reflector at least one second articulated part (2020a, 2020b, 2020c, 2020d).

[0153] This embodiment allows independent control of each of the first and second parts of the reflectors. It also allows the use of lower-power actuators 4220 and 4210 than those shown in Figures 7a and 7b. Finally, the absence of a transmission device reduces the number of potential technical problems.

[0154] According to one embodiment, the actuator may include an electric motor (brushless geared motor, or non-brushless or stepper motor), or a cylinder-type motor (electromechanical or hydraulic).

[0155] According to one embodiment, the reflecting device includes at least one control unit, configured to control at least one actuator and the transmission device so as to control the relative angular position of the first and second parts of each reflector, thus allowing adjustment of the focal area of ​​the reflecting surface or folding the first and second parts together to fold the reflector.

[0156] According to one embodiment, the transmission device may include a transmission box, a mechanical system such as a gearbox, cam box, and / or an electromechanical system with epicyclic gear train with power take-off on the main transmission shaft and timing movement by micromotors on differential.

[0157] According to one embodiment, environmental sensors such as sunlight sensors are used to properly control the reflectors according to the position of the sun in the sky.

[0158] According to one embodiment, the system is a focal length adjustment system for a reflector line according to the present invention, comprising at least one reflector according to the present invention and at least one receiver. The system is configured to adjust the focal zone position of at least one reflector according to the position of the sun and the receiver. This tracking of the sun's path ensures maximum sunlight exposure for the reflectors, but it is not sufficient on its own to significantly improve the efficiency of the solar power plant. The use of a "refocusing" function allows the focal zone of the reflectors to be adapted according to the position of the sun and the receiver in order to optimize the concentration of solar energy at the receiver.

[0159] According to another aspect, the invention relates to a solar field comprising at least one line of reflectors according to the invention and comprising at least one receiver intended to receive at least a part of the radiation reflected by the at least one line of reflectors.

[0160] According to one embodiment, the solar thermal power plant is a solar thermal power plant with linear concentrators, and preferably a Fresnel solar thermal power plant.

[0161] According to one embodiment, the present invention also relates to a solar thermal power plant with Fresnel reflectors whose efficiency is improved in part by refocusing the solar rays along the receivers throughout the day.

[0162] Furthermore, this solar thermal power plant, according to one embodiment, has an increased lifespan due to the possible protection of the reflectors by the present invention.

[0163] The present invention also relates to a method of orienting a reflecting device according to any one of claims 1 to 12. This method includes at least the following step: relative rotation, around the same axis of rotation, of at least a first and a second articulated part of the reflective surface of the reflector so as to follow the path of the sun and to make the linear focus, also called the focal zone, of the reflector coincide with the position of a receiver of the solar thermal power plant.

[0164] A non-limiting example of a solar field according to the present invention will now be described.

[0165] According to one embodiment, a solar field comprises between 8 and 20, advantageously between 10 and 18 and preferably 16 lines of reflectors.

[0166] According to one embodiment, the spacing between two lines of reflectors is between 0.2m and 3m, advantageously between 0.4m and 1.5m and preferably equal to 1.2m.

[0167] According to one embodiment, a solar field represents a spatial extent between 1000m2 and 50000m2, advantageously between 1500m2 and 25000m2 and preferably equal to 5000m2.

[0168] According to one embodiment, a line of reflectors has a length in linear meters between 50 and 500, advantageously between 100 and 300 and preferably equal to 200.

[0169] According to one embodiment, a reflector has a length in linear meters between 0.5 and 40, and advantageously between 1 and 20.

[0170] According to one embodiment, the opening of the parabola is between 0.5m and 2m, preferably between 0.75m and 1.5m and advantageously 1m.

[0171] According to one embodiment, the individual radius of curvature of at least one first articulated part 2010 is between 10m and 100m, advantageously between 15m and 50m and preferably equal to 20m.

[0172] According to one embodiment, the individual radius of curvature of at least one second articulated part 2020 is between 10m and 100m, advantageously between 15m and 50m and preferably equal to 20m.

[0173] According to one embodiment, the at least first articulated part 2010 comprises an individual radius of curvature equal to the individual radius of curvature comprised by the at least second articulated part 2020.

[0174] According to one embodiment, the at least first articulated part 2010 comprises an individual radius of curvature different from the individual radius of curvature comprised by the at least second articulated part 2020.

[0175] According to one embodiment, the overall radius of curvature of the reflective surface of reflector 2000 is between 10m and 100m, advantageously between 15m and 50m and preferably equal to 20m.

[0176] According to one embodiment, the height of a reflector is between 0.5m and 5m, advantageously between 0.75m and 3m and preferably equal to 1.5m.

[0177] According to one embodiment, the angular deviation between the longitudinal axis 2030 of the reflector 2000 and the North / South geographic axis is between 0° and 20°, advantageously between 0° and 10° and preferably equal to 0°.

[0178] The invention is not limited to the embodiments described above and extends to all embodiments covered by the claims.

Claims

1. Reflection device for a thermal solar power plant comprising at least one reflector (2000), the at least one reflector (2000) comprising at least one surface for reflecting sun rays, said at least one reflective surface being curved and having a focal zone, wherein said at least one reflective surface comprises at least one first portion (2010) and one second portion (2020) articulated so as to be able to follow the course of the sun and articulated against one another in rotation, the reflection device comprising a support (2050) intended to be fixed with respect to the ground and configured to support the first (2010) and second portions (2020), and wherein the first portion (2010) and the second portion (2020) are each articulated in rotation with respect to the support (2050) about one same axis of rotation (2030), characterised in that the first (2010) and second portions (2020) are configured such that the relative rotation thereof leads to a modification of the focal zone of the reflector (2000) so as to be able to maintain the focal distance and therefore the focal zone of the reflector (2000) at the level of a receiver of the power plant.

2. Reflection device according to the preceding claim, wherein the at least one reflector (2000) extends mainly about a longitudinal axis (2030) and wherein said axis of rotation is parallel to said longitudinal axis (2030).

3. Reflection device according to any one of the preceding claims, wherein at least one actuator (4200, 4210, 4220) is configured to drive in relative rotation the first (2010) and second (2020) portions, articulated against one another.

4. Reflection device according to the preceding claim, wherein the at least one actuator (4200) is configured to drive in relative rotation the first (2010) and second (2020) portions by way of at least one common motor shaft (4100) driving in rotation the first articulated portion (2010) and the second articulated position (2020) and preferably, wherein the reflection device comprises at least one transmission device (4110) coupled on the one hand to the at least one common motor shaft (4100) and coupled on the other hand to one from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions, the transmission device (4110) being configured such that when the motor shaft (4100) rotates, that from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions coupled to the transmission device (4110) rotates at a speed different from the other from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions.

5. Reflection device according to any one of claims 1 and 2, wherein at least two actuators (4210, 4220), coupled respectively to one of the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions and configured to drive in relative rotation the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions.

6. Reflection device according to any one of the preceding claims, wherein the tangents at each of the surface portions carried by the first and second portions, taken at the level of the respective axes of rotation of the first and second portions, together form an angle α, and wherein the reflection device is configured to make it possible for an evolution of the angle α between 0° and 300°, advantageously between 0° and 180° and preferably between 160° and 180°, and preferably wherein the at least one reflector (2000) is configured to permit a so-called cleaning configuration, wherein the angle α is greater than or equal to 180° and preferably greater than 270° and preferably greater than 300°.

7. Reflection device according to any one of the preceding claims, comprising a plurality of reflectors aligned to form a line of reflectors, each reflector (2000) mainly extending about a longitudinal axis (2030) and the line of reflectors extending about said longitudinal axis (2030), and wherein said longitudinal axis (2030) is parallel to the North / South geographic axis.

8. Reflection device according to the preceding claim, comprising at least one transmission motor shaft (4100), preferably one single transmission motor shaft (4100), coupled to an actuator (4200), preferably one single actuator (4200), the motor shaft (4100) being configured to drive in rotation said first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions of the line of reflectors.

9. Reflection device according to the preceding claim, the reflection device comprising one single motor shaft for the line of reflectors and comprising, for each reflector of the line of reflectors, at least one transmission device (4110, 4110...) coupled on the one hand to the single motor shaft (4110, 4110...) and coupled on the other hand to one from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions of the reflector, the transmission device (4110, 4110...) being configured such that when the motor shaft (4110, 4110...) rotates, that from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions coupled to the transmission device (4110, 4110...) rotates at a speed different from the other from among the first (2010, 2010a, 2010b, 2010c, 2010d) and the second (2020, 2020a, 2020b, 2020c, 2020d) portions.

10. Reflection device according to any one of claims 7 or 8, comprising at least one first transmission motor shaft (4130) configured to drive in rotation the at least one first portion (2010, 2010a, 2010b, 2010c, 2010d) of each reflector of the line of reflectors and comprising at least one second transmission motor shaft (4120), different from the first motor shaft (4130), configured to drive in rotation the at least one second portion (2020, 2020a, 2020b, 2020c, 2020d) of each reflector of the line of reflectors.

11. Reflection device according to the preceding claim, comprising: - an actuator (4200) configured to drive in rotation, both the first motor shaft (4130) and the second motor shaft (4120), the reflection device comprising at least one transmission device (4110) coupled to the actuator (4200) and to at least one from among the first (4130) and second (4120) motor shafts, the transmission device (4110) being configured such that the first (4130) and second (4120) motor shafts can rotate at different speeds when the actuator (4200) functions so as to make the angle separating the first and second portions of each reflector vary, or - a first actuator (4210) configured to drive in rotation the at least one first motor shaft (4130) and a second actuator (4220), different from the first actuator (4210), configured to drive in rotation the at least one second transmission motor shaft (4120).

12. Reflection device according to any one of claims 3, 4, 6, 8 and 11, comprising at least one control unit (4000, 4010, 4020), configured to control the at least one actuator (4200, 4210, 4220) so as to control the relative angular position of the first and second portions of each reflector.

13. Solar power plant comprising at least one reflection device according to any one of the preceding claims, and comprising at least one receiver (3000) intended to receive at least some of the radiation reflected by the at least one reflection device, said system being configured to adjust the position of the focal zone of the reflective surface of each reflector (2000), by adjusting the relative angular position between the at least one first (2010) and one second (2020) portions of each reflector (2000), according to the position of the sun and / or of that of the receiver (3000).

14. Solar power plant according to the preceding claim, wherein the at least one device is configured to be arranged on one side or on the other side only of the receiver (3000) with respect to the vertical passing through the receiver (3000).

15. Method for orienting a reflection device according to any one of claims 1 to 12, the method comprising at least the following step: relative rotation, about one same axis of rotation (2030), first (2010) and second (2020) portions of the reflective surface of the reflector so as to make the focal zone of the reflector coincide with or approach the position of a receiver (3000) of the thermal solar power plant.