DE102022106138A1 - Parabolic trough collector arrangement with a preheating device and method for operating a parabolic trough collector arrangement with a preheating device - Google Patents

Abstract

The invention relates to a parabolic trough collector arrangement (1000) comprising a parabolic trough collector (10) with a reflective reflector surface (16), which has a focal point line (26) along its longitudinal extent (50) in which an absorber tube (20) is arranged, and comprising a Device (100) for preheating an absorber tube (20) of the parabolic trough collector (10), the device (100) having at least one mirror element (30) with a longitudinal axis (52) which is located away from the absorber tube (20) on one of the reflector surface (16) facing side of the absorber tube (20) is arranged along the longitudinal extent (50) with its longitudinal axis (52) parallel to a vertex line (28) of the parabolic trough collector (10).

Description

State of the art

The invention relates to a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector and a method for operating a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector.

In parabolic trough power plants, various media are used to absorb and dissipate the concentrated heat in the absorber tube. Oil is currently commonly used as a heat transfer medium. In order to be able to achieve higher temperatures, the use of salt as a heat transfer medium is being investigated. Since salts freeze at temperatures between 140°C and 240°C, the pipes must be kept in a temperature range that is above these temperatures. This happens when the sun shines through the salt flowing through it, which is heated by the sun. When no sun is concentrated on the absorber tube, such as at night, keeping warm is done by hot salt from storage tanks. However, technical defects can mean that salt can no longer be pumped through the pipes.

In this case, the plan so far is to heat the absorber tube with an impedance heater. To do this, electrical poles are attached to the beginning and end of the absorber pipeline, through which an electrical current flows. However, this technology entails prohibitively high costs, especially because of the expensive copper cables that have to be laid.

Disclosure of the invention

The object of the invention is to create a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector, which is simple and inexpensive to implement.

A further object is to provide a method for operating a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector, which is simple and inexpensive to implement.

The tasks are solved by the features of the independent claims. Favorable refinements and advantages of the invention result from the further claims, the description and the drawing.

According to one aspect of the invention, a parabolic trough collector arrangement is proposed, comprising a parabolic trough collector with a reflective reflector surface, which has a focal point line along its longitudinal extent in which an absorber tube is arranged. The parabolic trough collector arrangement further comprises a device for preheating an absorber tube of the parabolic trough collector.

The device has at least one mirror element with a longitudinal axis, which is arranged away from the absorber tube on a side of the absorber tube facing the reflector surface along the longitudinal extent with its longitudinal axis parallel to a vertex line of the parabolic trough collector.

The proposed parabolic trough collector arrangement has at least one mirror element, for example a flat mirror element, which is arranged as a preheating mirror at the apex of the parabolic trough collector. The at least one mirror element is advantageously not aligned parallel to the tangential surface of the vertex, but is inclined at an angle, so that the absorber tube is simply illuminated with solar radiation when the parabolic trough collector is rotated slightly from the position that focuses the solar radiation onto the absorber tube.

The at least one mirror element can, for example, be arranged in an area that is otherwise not used when focusing the parabolic trough collector, for example between the parabolically shaped mirrors. The parabolic trough collector usually consists of individual collector segments strung together. The individual collector segments can consist of two parabolically shaped partial mirrors, each with a reflective reflector surface, so that a continuous longitudinal slot is created at the apex of the overall parabolic course of collector segments lined up next to one another. The at least one mirror element can at least partially cover the longitudinal slot and/or be arranged with its holder in the longitudinal slot.

The at least one mirror element can, for example, have the width of the glass cladding tube which surrounds the absorber tube.

The advantage lies in increased irradiation of the absorber tube, since the absorber tube is irradiated directly by solar radiation on its front side facing the sun and by reflected solar radiation from the at least one mirror element on its back side facing the parabolic trough collector. This allows the necessary expansion mung of the absorber tube to maintain the desired temperature range.

The proposed device for preheating the absorber tube has the advantage that since the absorber tube is illuminated with sunlight from the front and the back, one-sided heating of the absorber tube, which can lead to considerable mechanical stresses in the absorber tube, can advantageously be avoided .

The proposed device also has particular advantages over a possible heating of the absorber tube with a partially focused parabolic trough collector, with which sunlight can also be directed onto the absorber tube from the back, i.e. from the reflector surface.

By partially focusing the parabolic trough collector in this way, sufficient energy can be provided and the mechanical stresses can also be reduced. However, focusing too strongly can easily lead to local overheating, resulting in unacceptable stresses in the absorber tube. Therefore, highly accurate tracking is required over the entire distance of the parabolic trough collector, which is, for example, approx. 120 m long.

Due to inaccuracies in assembly and various forces acting on the parabolic trough collector, it cannot be expected that the absorber tube will be heated sufficiently uniformly without locally unacceptable overheating. Due to the high heat input during partial focusing, it is also necessary to limit the input to short times, so that the parabolic trough collector must be swiveled in and out at short intervals.

With the proposed device, risks caused by local overheating of the absorber tube can be advantageously avoided.

The investment costs for the at least one additional mirror element for preheating are low in relation to the costs of induction heating.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be arranged inclined about its longitudinal axis at an angle relative to a tangential plane of the apex line. With such an arrangement, the parabolic trough collector can advantageously be aligned so that the sunlight reflected by the mirror element falls on the absorber tube and the absorber tube is thus heated. In such an orientation of the parabolic trough collector, the sunlight focused by the reflector surface of the parabolic trough collector is then radiated laterally past the absorber tube. This prevents the absorber tube from heating up too much.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be arranged along a vertex line of the parabolic trough collector.

Conveniently, the at least one mirror element can be arranged in an area which is shaded anyway during the focusing operation of the parabolic trough collector and cannot be used for the actual collector operation.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be arranged laterally offset in the direction of the absorber tube from the apex line of the parabolic trough collector.

In particular, the mirror element can be arranged at least partially outside the reflector surface. A position outside to the side of the parabolically shaped reflector surface of the parabolic trough collector is also possible for arranging the mirror element. The radiation conditions may be somewhat less favorable in such an arrangement because the reflected sunlight falls slightly obliquely onto the absorber tube. Nevertheless, sufficient heating of the absorber tube can be achieved.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be flat. A flat mirror can be easily aligned and represents a cost-effective option for a device for preheating the absorber tube.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be concavely curved in the direction of the absorber tube. In particular, the mirror element can be curved parabolically in the direction of the absorber tube. Such a focusing design of a mirror element can also be used advantageously for a device for preheating the absorber tube.

With a favorable design of the parabolic trough collector arrangement, little can happen at least one mirror element can be arranged at a distance from the reflector surface of the parabolic trough collector. The mirror element can, for example, be arranged offset in front of the apex line of the parabolic trough collector in the direction of the absorber tube. In this way, the mirror element can be easily installed. A corresponding holder for the mirror element can also be attached cheaply.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be formed in one piece with the reflector surface of the parabolic trough collector, at least in some areas. In an alternative embodiment, the mirror element can also advantageously be manufactured, for example cast, with the actual mirror segment of the parabolic trough collector. The mirror element then forms one part with the reflector surface of the parabolic trough collector. This means that the mirror element does not require its own suspension.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be arranged to be movable relative to the parabolic trough collector. This allows the mirror element to be aligned independently of the orientation of the parabolic trough collector in order to direct the reflected solar radiation onto the absorber tube. To align the at least one mirror element, a separate regulation and/or control unit can be provided, which regulates or controls the alignment device in order to move the at least one mirror element.

Alternatively, the device for aligning the at least one mirror element can be regulated or controlled by a regulating and/or control unit of the parabolic trough collector.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can have a device for aligning relative to the absorber tube. This allows the mirror element to be aligned independently of the orientation of the parabolic trough collector in order to direct the reflected sunlight onto the absorber tube.

The at least one mirror element can also advantageously be tracked to the position of the sun without the entire parabolic trough collector arrangement, which can include, for example, a parabolic trough collector with a large number of individual collector segments, having to be tracked.

According to a favorable embodiment of the parabolic trough collector arrangement, one or more mirror elements can be arranged one after the other in the longitudinal extent of the parabolic trough collector. In particular, the one or more mirror elements can essentially cover the longitudinal extent of the parabolic trough collector. As a result, the absorber tube, which usually covers the entire longitudinal extent of the parabolic trough collector arrangement, can be advantageously heated over its entire length.

According to a favorable embodiment of the parabolic trough collector arrangement, the at least one mirror element can be arranged in the area of a shadow cast by the absorber tube illuminated by solar radiation when the parabolic trough collector is focused on the absorber tube during normal operation.

The mirror element can advantageously be arranged in an area which is shaded anyway during the focusing operation of the parabolic trough collector and cannot be used for the actual collector operation

According to a favorable embodiment of the parabolic trough collector arrangement, a width of the solar radiation reflected by the mirror element at the location of the absorber tube can correspond to a diameter of a glass cladding tube of the absorber tube. In this way, the entire width of the glass cladding tube can be illuminated by the solar radiation reflected on the at least one mirror element. This allows the absorber tube to be supplied with the necessary energy for heating as expediently as possible.

According to a favorable embodiment of the parabolic trough collector arrangement, a width of the at least one mirror element, in particular the flat mirror element, can correspond to the diameter of the glass cladding tube of the absorber tube. In this way, the entire width of the glass cladding tube can be illuminated by the solar radiation reflected on the mirror element. This allows the absorber tube to be supplied with the necessary energy for heating as expediently as possible.

According to a further aspect of the invention, a method for operating a parabolic trough collector arrangement is proposed, comprising a parabolic trough collector with a reflective reflector surface, which has a focal line along its longitudinal extent in which an absorber tube is arranged, and comprising a device for preheating the absorber tube of the parabolic trough collector.

The device has at least one mirror element with a longitudinal axis, which is arranged away from the absorber tube on a side of the absorber tube facing the reflector surface along the longitudinal extent with its longitudinal axis parallel to a vertex line of the parabolic trough collector. To preheat the absorber tube, the parabolic trough collector is aligned in such a way that solar radiation focused by the parabolic trough collector radiates past the absorber tube to the side.

The at least one mirror element is aligned so that solar radiation reflected on the at least one mirror element falls on the side of the absorber tube that faces the reflector surface.

With the proposed method, the absorber tube can be advantageously preheated, since the absorber tube is irradiated directly by solar radiation on its front side facing the sun and by reflected solar radiation from the mirror element on its back side facing the parabolic trough collector. This allows the necessary heating of the absorber tube to be achieved to maintain the desired temperature range.

Because the absorber tube is illuminated with sunlight from the front and back, one-sided heating of the absorber tube with sunlight, which can lead to considerable mechanical stresses in the absorber tube, can advantageously be avoided.

The proposed method is also significantly more advantageous than partial focusing with the parabolic trough collector as an alternative to preheating the parabolic trough collector. With the proposed method, risks caused by local overheating can be advantageously avoided.

According to a favorable embodiment of the method, the at least one mirror element can be aligned together with the parabolic trough collector in such a way that solar radiation reflected on the at least one mirror element falls on the side of the absorber tube that faces the reflector surface.

The common alignment of the at least one mirror element with the parabolic trough collector has the advantage that the focused solar radiation of the reflector surface can automatically be radiated laterally past the absorber tube, while the solar radiation reflected by the mirror element is directed onto the absorber tube. The only requirement for this is that the mirror element is arranged inclined about its longitudinal axis at an angle relative to a tangential plane of the apex line. In this way, the absorber tube can be preheated cheaply.

According to a favorable embodiment of the method, the at least one mirror element can be aligned independently of the parabolic trough collector, in particular with an alignment device connected to the mirror element, so that solar radiation reflected on the mirror element falls on the side of the absorber tube facing the reflector surface. This allows the mirror element to be aligned independently of the orientation of the parabolic trough collector in order to direct the reflected sunlight onto the absorber tube.

The mirror element can also advantageously be tracked to the position of the sun without the entire parabolic trough collector arrangement, which can include, for example, a parabolic trough collector with a large number of individual collector segments, having to be tracked.

According to a favorable embodiment of the method, the mirror element can be tracked with the position of the sun in such a way that when the position of the sun changes, the reflected solar radiation continues to fall on the side of the absorber tube facing the reflector surface. In this way, permanent and uniform heating of the absorber tube by the solar radiation reflected on the mirror element is advantageously possible.

drawing

Further advantages result from the following drawing description. Exemplary embodiments of the invention are shown in the figures. The figures, the description and the claims contain numerous features in combination. The person skilled in the art will also expediently consider the features individually and combine them into further sensible combinations.

• 1 einen Querschnitt durch eine Parabolrinnenkollektoranordnung mit einer Vorrichtung zum Vorwärmen eines Absorberrohrs eines Parabolrinnenkollektors nach einem Ausführungsbeispiel der Erfindung;
• 2 eine perspektivische Ansicht der Parabolrinnenkollektoranordnung nach 1; und
• 3 einen Querschnitt durch eine Parabolrinnenkollektoranordnung mit einer Vorrichtung zum Vorwärmen eines Absorberrohrs eines Parabolrinnenkollektors nach einem weiteren Ausführungsbeispiel der Erfindung.

They show, for example:

• 1 a cross section through a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector according to an embodiment of the invention;
• 2 a perspective view of the parabolic trough collector arrangement 1 ; and
• 3 a cross section through a parabolic trough collector arrangement with a device for preheating an absorber tube of a parabolic trough collector according to a further embodiment of the invention.

Embodiments of the invention

In the figures, components of the same type or with the same effect are numbered with the same reference numerals. The figures only show examples and are not to be understood as limiting.

Directional terminology used below with terms such as “left”, “right”, “top”, “bottom”, “before”, “behind”, “after” and the like only serves to better understand the figures and is in no way intended to limit the represent generality. The components and elements shown, their design and use can vary according to the considerations of a person skilled in the art and can be adapted to the respective applications.

1 shows a cross section through a parabolic trough collector arrangement 100 with a device 100 for preheating an absorber tube 20 of a parabolic trough collector 10 according to an exemplary embodiment of the invention, while in 2 a perspective view of the parabolic trough collector arrangement 1000 1 is shown.

The parabolic trough collector arrangement 1000 includes a parabolic trough collector 10 with a reflective reflector surface 16, which has a large number of individual collector segments 11. The individual collector segments 11 consist of two unspecified parabolically shaped partial mirrors, so that a continuous longitudinal slot 60 results in the apex of the overall parabolic course of collector segments 11 lined up next to one another.

A collector segment 11 has a length 18. The partial mirrors of each collector segment 11 are separated by the longitudinal slot 60 and extend away from it.

The collector segments 11 are arranged one after the other in the longitudinal extent 50 of the parabolic trough collector 10 and are aligned parallel. The parabolic trough collector 10 has a focal point line 26 along its longitudinal extent 50, in which an absorber tube 20 is arranged. The parabolic trough collector arrangement 1000 further comprises a device 100 for preheating an absorber tube 20 of the parabolic trough collector 10.

The device 100 points to this, as in particular in 2 can be seen, a series of mirror elements 30 with a longitudinal axis 52, which are arranged on a side of the absorber tube 20 facing the reflector surface 16 along the longitudinal extension 50 with their longitudinal axis 52 parallel to a vertex line 28 of the parabolic trough collector 10. The length 32 of the respective mirror element 30 corresponds to the length 18 of the respective collector segment 11.

The mirror elements 30 are arranged in the area of the longitudinal slot 60 and cover it at least partially or completely. As in the cross section in 1 As can be seen, the respective flat mirror element 30 lies at the apex 28 of the parabola of the parabolic trough collector 10 below the absorber tube 20.

The respective mirror element 30 is slightly inclined in relation to the tangent or tangential plane 14 of the vertex 28 of the parabola. The incident solar radiation 40 is reflected by the mirror element 30 and the reflected solar radiation 42 is directed onto the absorber tube 20.

In addition, the absorber tube 20 is illuminated by the sun through direct solar radiation 40. Because not only radiation from the sunny side, but also reflected solar radiation 42 from the mirror element 30 falls on the absorber tube 20, the heat is distributed more evenly over the circumference of the tube. Due to the additional irradiation of the solar radiation 42 reflected on the mirror element 30, a higher temperature of the absorber tube 20 is also achieved.

The respective mirror element 30 is inclined and not arranged parallel to the tangential plane 14 so that the parabolic mirror on both sides does not also concentrate sunlight onto the absorber tube 20. Otherwise the absorber tube 20 would become too hot. The parabolic trough collector 10 is rotated to preheat the absorber tube 20 so that the sun is directed from the flat mirror element 30 onto the absorber tube 20.

The mirror elements 30 are arranged one after the other in the longitudinal extent 50 of the parabolic trough collector 10. In this way, the mirror elements 30 essentially cover the longitudinal extent 50 of the parabolic trough collector 10. The flat mirror elements 30 are located under the full length of the absorber tube 20.

As a result, the absorber tube 20, which usually covers the entire longitudinal extent 50 of the parabolic trough collector arrangement 1000, can be advantageously heated over its entire length. The mirror element 30 can expediently be so long, for example, that it can be arranged just between the holders 22 of the absorber tube 20, as in the exemplary embodiment in 2 is shown.

Like in the 1 and 2 As can be seen, the mirror elements 30 are arranged along the apex line 28 of the parabolic trough collector 10. The mirror elements 30 can be mounted through the longitudinal slot 60, which is not shown in the figures. The mirror elements 30 that follow one another along the longitudinal extent 50 can be tilted relative to one another by a small angle about their longitudinal axis from one mirror element 30 to the next mirror element 30 in order to follow any torsion of the parabolic trough collector 10 along its longitudinal extent 50.

In such an arrangement, the mirror elements 30 are arranged in the area of a shadow cast by the absorber tube 20 illuminated by the solar radiation 40 when the parabolic trough collector 10 is focused on the absorber tube 20 during normal operation. The mirror elements 30 are arranged in an area of the parabolic trough collector 10 which is not required for the intended operation of the parabolic trough collector 10.

The mirror elements 30 are arranged inclined about their longitudinal axis 52 at an angle 36 relative to a tangential plane 14 adjacent to the apex line 28.

It is sufficient if the angle 36 by which the mirror elements 30 are tilted relative to the tangential plane 14 is, for example, in the range of 5° to 10°. In this way, the parabolic trough collector 10 is sufficiently defocused when the parabolic trough collector 10 is aligned such that the solar radiation 42 reflected on the mirror elements 30 falls on the absorber tube 20.

According to the proposed method for preheating the absorber tube 20 of the parabolic trough collector 10, the parabolic trough collector 10 is aligned for preheating the absorber tube 20 in such a way that solar radiation focused by the parabolic trough collector 10 is radiated laterally past the absorber tube 20. Furthermore, the mirror elements 30 are then aligned so that solar radiation 42 reflected on the mirror element 30 falls on a side of the absorber tube 20 facing the reflector surface 16.

The mirror elements 30 are aligned together with the parabolic trough collector 10 so that solar radiation 42 reflected on the mirror element 30 falls on the side of the absorber tube 20 facing the reflector surface 16.

The mirror elements 30 are arranged at a distance from the reflector surface 16 of the parabolic trough collector 10, i.e. lie slightly above the apex line 28 in the direction of the absorber tube 20 in front of the reflector surface 16.

The mirror elements 30 are designed as flat mirrors. The reflected solar radiation 42 is therefore not focused.

In an alternative embodiment, not shown, the mirror elements 30 can be designed to be concavely curved in the direction of the absorber tube 20, for example, in particular parabolically curved.

The reflected solar radiation 42 could thus be directed onto the absorber tube 20 in a focused manner. A smaller area of the mirror elements 30 would be sufficient for this. However, higher demands would be placed on the alignment of the mirror elements 30 on the absorber tube 20 and on the suspension of the mirror elements 30.

To preheat the absorber tube 20, it is sufficient if a width 44 of the solar radiation 42 reflected by the mirror element 30 at the location of the absorber tube 20 corresponds to a diameter 24 of a glass cladding tube 38 of the absorber tube 20.

In the case of a flat mirror element 30, it may be expedient if a width 34 of the mirror element 30 corresponds to the diameter 24 of the glass cladding tube 38 of the absorber tube 20 in order to be able to cover the entire width of the absorber tube 20 with the reflected solar radiation 42. In this way, the entire width of the glass cladding tube 38 can be illuminated by the solar radiation 42 reflected on the mirror element 30. As a result, the absorber tube 20 can be supplied with the necessary energy for heating as expediently as possible.

The mirror elements 30 can expediently be mechanically connected to a support structure 12 of the parabolic trough collector 10. In this case, the entire parabolic trough collector 10 is moved when the mirror elements 30 are aligned so that the reflected solar radiation 42 falls on the absorber tube 20.

In an alternative embodiment, not shown, the mirror elements 30 can be arranged to be movable relative to the parabolic trough collector 10.

The mirror elements 30 can have a device for aligning relative to the absorber tube 20, so that they can be aligned independently of the parabolic trough collector 10 so that the reflected solar radiation 42 falls on the side of the absorber tube 20 facing away from the sun. The parabolic trough collector 10 must but in this case must be defocused separately, since the absorber tube 20 could otherwise be locally overheated.

The respective mirror element 30 can also advantageously be tracked in this way to the position of the sun without the entire parabolic trough collector arrangement 1000, which can include, for example, a parabolic trough collector 10 with a large number of individual collector segments 11, having to be tracked.

The device for aligning the mirror elements 30 can engage the holder of the mirror elements 30 through the longitudinal slot 60. The individual mirror elements 30 can advantageously be moved individually. This makes it possible to follow any torsion of the parabolic trough collector 10 along its longitudinal extent 50 when aligning the mirror elements 30.

The device for aligning the mirror elements 30 relative to the absorber tube 20 can be regulated or controlled with a separate regulation and/or control unit in order to move the mirror elements 30. Alternatively, the device for aligning the mirror elements 30 relative to the absorber tube 20 can be regulated or controlled by a regulating and/or control unit of the parabolic trough collector 10.

In a further embodiment, not shown, the mirror elements 30 can be arranged laterally offset in the direction of the absorber tube 20 from the apex line 28 of the parabolic trough collector 10.

In particular, the mirror elements 30 can also be arranged at least partially outside the reflector surface 16. A position on the outside of the parabolically shaped reflector surface 16 of the parabolic trough collector 10 for arranging the mirror element 10 is also possible.

The radiation conditions may possibly be somewhat less favorable in such an arrangement, since the reflected solar radiation 42 falls slightly obliquely onto the absorber tube 20. Nevertheless, sufficient heating of the absorber tube 20 can be achieved.

The mirror elements 30 can expediently be tracked with the position of the sun in such a way that when the position of the sun changes, the reflected solar radiation 42 continues to fall on the side of the absorber tube 20 facing the reflector surface 16.

3 shows a cross section through a parabolic trough collector arrangement 1000 with a device 100 for preheating an absorber tube 20 of a parabolic trough collector 10 according to a further exemplary embodiment of the invention.

In this exemplary embodiment, the respective mirror element 30 is connected with a longitudinal edge directly to a collector segment 11 of the parabolic trough collector 10 and protrudes obliquely from it.

The mirror element 30 can be formed in one piece with the reflector surface 16 of the parabolic trough collector 10 at least in some areas. In this embodiment, the mirror element 30 can also advantageously be manufactured, for example cast, with the actual partial mirror segment of the parabolic trough collector 10.

The respective mirror element 30 then forms a component with the reflector surface 16 of the parabolic trough collector 10. The mirror element 30 does not require its own suspension and can be moved overall with the parabolic trough collector 10.

Reference symbols

10

Parabolic trough collector

11

collector segment

12

Support structure

14

Tangent plane

16

Reflector surface

18

Length of parabolic trough reflector

20

absorber tube

22

Holder absorber tube

24

Diameter of absorber tube

26

Focal point line

28

Vertex line

30

Mirror element

32

Length of mirror element

34

Wide mirror element

36

angle

38

Glass cladding tube

40

direct sunlight

42

reflected solar radiation

44

Broad solar radiation

50

Longitudinal extension

52

Longitudinal axis

60

Longitudinal slot

100

contraption

1000

Parabolic trough collector arrangement

Claims (18)

Parabolic trough collector arrangement (1000) comprising a parabolic trough collector (10) with a reflective reflector surface (16), which has a focal point line (26) along its longitudinal extent (50) in which an absorber tube (20) is arranged, and comprising a device (100) for preheating an absorber tube (20) of the parabolic trough collector (10), the device (100) having at least one mirror element (30) with a longitudinal axis (52) which is located away from the absorber tube (20) on a surface facing the reflector (16). Side of the absorber tube (20) is arranged along the longitudinal extent (50) with its longitudinal axis (52) parallel to a vertex line (28) of the parabolic trough collector (10). Parabolic trough collector arrangement Claim 1 , wherein the at least one mirror element (30) is arranged inclined about its longitudinal axis (52) at an angle (36) relative to a tangential plane (14) of the apex line (28). Parabolic trough collector arrangement Claim 1 or 2 , wherein the at least one mirror element (30) is arranged along a vertex line (28) of the parabolic trough collector (10). Parabolic trough collector arrangement Claim 1 or 2 , wherein the at least one mirror element (30) is arranged in the direction of the absorber tube (20) laterally offset from the apex line (28) of the parabolic trough collector (10), in particular wherein the mirror element (30) is arranged at least partially outside the reflector surface (16). is. Parabolic trough collector arrangement according to one of the preceding claims, wherein the at least one mirror element (30) is flat. Parabolic trough collector arrangement according to one of the Claims 1 until 4 , wherein the at least one mirror element (30) is concavely curved in the direction of the absorber tube (20), in particular wherein the mirror element (30) is parabolically curved in the direction of the absorber tube (20). Parabolic trough collector arrangement according to one of the preceding claims, wherein the at least one mirror element (30) is arranged at a distance from the reflector surface (16) of the parabolic trough collector (10). Parabolic trough collector arrangement according to one of the preceding claims, wherein the at least one mirror element (30) is at least partially formed in one piece with the reflector surface (16) of the parabolic trough collector (10). Parabolic trough collector arrangement according to one of the preceding claims, wherein the at least one mirror element (30) is arranged to be movable relative to the parabolic trough collector (10). Parabolic trough collector arrangement Claim 9 , wherein the at least one mirror element (30) has a device for aligning relative to the absorber tube (20). Parabolic trough collector arrangement according to one of the preceding claims, wherein one or more mirror elements (30) are arranged successively in the longitudinal extent (50) of the parabolic trough collector (10), in particular wherein the one or more mirror elements (30) the longitudinal extent (50) of the parabolic trough collector (10) essentially cover. Parabolic trough collector arrangement according to one of the preceding claims, wherein the mirror element (30) is arranged in the area of a shadow cast by the absorber tube (20) illuminated by the solar radiation (40) when the parabolic trough collector (10) is focused on the absorber tube (20) during normal operation. Parabolic trough collector arrangement according to one of the preceding claims, wherein a width (44) of the solar radiation (42) reflected by the mirror element (30) at the location of the absorber tube (20) corresponds to a diameter (24) of a glass cladding tube (38) of the absorber tube (20). Parabolic trough collector arrangement Claim 12 , wherein a width (34) of the mirror element (30), in particular of the flat mirror element (30), corresponds to the diameter (24) of the glass cladding tube (38) of the absorber tube (20). Method for operating a parabolic trough collector arrangement (1000) according to one of the preceding claims, comprising a parabolic trough collector (10) with a reflective reflector surface (16), which has a focal point line (26) along its longitudinal extent (50), in which an absorber tube (20) is arranged, and comprising a device (100) for preheating the absorber tube (20) of the parabolic trough collector (10), the device (100) having at least one mirror element (30) with a longitudinal axis (52) which is remote from the absorber tube (20) on a side of the absorber tube (20) facing the reflector surface (16) along the first longitudinal strip ckung (50) is arranged with its longitudinal axis (52) parallel to an apex line (28) of the parabolic trough collector (10), the parabolic trough collector (10) being aligned for preheating the absorber tube (20) in such a way that solar radiation focused by the parabolic trough collector (10). is radiated laterally past the absorber tube (20), the mirror element (30) being aligned in such a way that solar radiation (42) reflected on the mirror element (30) falls on the side of the absorber tube (20) that corresponds to the reflector surface (16). is facing. Procedure according to Claim 15 , wherein the mirror element (30) is aligned together with the parabolic trough collector (10) so that solar radiation (42) reflected on the mirror element (30) falls on the side of the absorber tube (20) that faces the reflector surface (16). . Procedure according to Claim 15 , wherein the mirror element (30) is aligned independently of the parabolic trough collector (10), in particular with an alignment device connected to the mirror element (30), so that solar radiation (42) reflected on the mirror element (30) is directed onto the reflector surface (16) facing side of the absorber tube (20). Procedure according to one of the Claims 15 until 17 , wherein the mirror element (30) is tracked with the position of the sun so that when the position of the sun changes, the reflected solar radiation (42) continues to fall on the side of the absorber tube (20) facing the reflector surface (16).

Images