WO2024056658A1 - Solar-thermal module - Google Patents

Abstract

The invention relates to a solar-thermal module as part of a solar-thermal receiver with a high level of thermal efficiency for the absorption of solar radiation for heating a heat carrier medium flowing inside each solar-thermal module. The invention also relates to a solar-thermal receiver comprising the solar-thermal modules according to the invention. The invention further relates to a method for using the solar-thermal receiver.

Description

Description

Solar thermal module

The present invention relates to a solar thermal module for the absorption of concentrated solar radiation for heating a heat transfer medium flowing inside the module. The present invention further relates to a solar thermal receiver comprising the solar thermal modules according to the invention. The present invention also relates to a method for using the solar thermal receiver.

Solar thermal energy is basically a well-known area and appropriate solutions have been discussed for many years to efficiently generate energy from solar radiation. Nevertheless, practical problems question the widespread use of solar thermal tower systems, for example. Such solar thermal tower systems include a tower, a solar thermal receiver, which is arranged in the upper area of the tower and heats a heat transfer medium there, and a large number of heliostats arranged on the floor, which are aligned in such a way that their mirrors reflect the solar radiation to the receiver. In the receiver, the concentrated solar radiation is converted into heat and transferred to the heat transfer medium. The heated heat transfer medium is then fed to a suitable heat consumer or a heat storage device for later use.

For example, the patent EP 2 520 872 B1 discloses, in particular in FIG. 4, a solar thermal module which is used as a solar thermal receiver comprising several solar thermal modules similar to EP 2 520 872 B1, FIG should be able to be. Due to the special shape of the outer surface with elevations and depressions, such receivers promise higher efficiency than conventional receivers for heating a heat transfer medium with a smooth outer surface. The cold heat transfer medium becomes namely, inside such a special solar thermal module, it is directed directly to its respective elevation and thus cools it particularly effectively. The heat transfer medium then flows inside the module towards the depressions on the outer surface, is heated further and finally leaves the respective solar thermal module. On the outer surfaces of the elevations, solar heat that is not absorbed is not completely radiated into the surroundings and would therefore be lost, but rather radiates partially onto the adjacent elevations, so that part of this heat can also be absorbed and dissipated by the heat transfer medium.

In practice, however, it turns out that such solar thermal modules are not used because many details of the technical implementation are unresolved. These include, for example, the compensation of thermal expansion while maintaining mechanical stability of the modules, the appropriate sealing of the flow paths and the adequate cooling of all thermally loaded components.

Therefore, there is still a problem in heating the heat transfer medium with a suitable solar thermal module similar to EP 2 520 872 Bl, Figure 4, in such a way that due to the special shape of the outer surface of a solar thermal receiver made up of several modules similar to EP 2 520 872 Bl , Figure 2, results in a particularly high level of efficiency. This special shape of the outer surface, which is required for high efficiency, includes the property that the cold heat transfer medium should cool the front tip of the solar thermal module on its inside, and then flow away to the rear as it heats up further. For this purpose, the inflowing cold heat transfer medium must necessarily be guided through the flow area of the hot outflowing heat transfer medium. In particular, there are the problems that the hot and cold zones of the solar thermal module must be sufficiently insulated from each other and thermal expansion must be adequately compensated for. and the receiver must be sufficiently mechanically resilient and sufficiently tight. There are large temperature differences in the solar thermal module because its outside is exposed to highly concentrated solar radiation, while the inflowing heat transfer medium has a low temperature and the outflowing medium has a high temperature.

These and other problems are solved by the devices and methods described below. Further advantageous embodiments can be found in the dependent claims and the detailed description. These benefits can be used to tailor a solution to specific needs or to solve additional problems.

According to one aspect, the present invention relates to a solar thermal module suitable for use as a component of a solar thermal receiver for the absorption of solar radiation for heating a heat transfer medium flowing inside the solar thermal module with the following features, wherein the solar thermal module has an absorption region for solar radiation, wherein the absorption region has an outer surface, wherein the outer surface of the absorption region is essentially convex in the form of a cap, the absorption region being impermeable to solar radiation, the solar thermal module being suitable for being connected to a heat transfer medium supply channel, from which the heat transfer medium enters the solar thermal module , wherein the solar thermal module is adapted so that the supplied heat transfer medium flows through the solar thermal module through at least one inner tube, the heat transfer medium inside the solar thermal module first being guided to the top of the absorption area, wherein the heat transfer medium is guided from the tip of the absorption region inside the solar thermal module along the remaining absorption region, wherein the solar thermal module is adapted so that the heat transfer medium leaves through an outlet into a heat transfer medium discharge channel, wherein the at least one inner tube comprises an inner tube A, wherein a Section of the inner tube A is adapted to run through the heat transfer medium discharge channel, the section of the inner tube A being enclosed by an outer tube, the outer tube being adapted to form part of the wall of the heat transfer medium discharge channel, the solar thermal module having at least one spring element in the force flow between the inner tube A and the outer tube, wherein the at least one spring element is adapted to compensate for different thermal expansion of the inner tube A and the outer tube, the at least one spring element having a spring force which is transmitted in the inner tube A as a tensile force and in the outer tube as a compressive force.

It was observed that such a construction of the solar thermal module enables thermal stresses to be significantly minimized. It was also found that the solar thermal modules according to the invention provide a higher thermal efficiency. The solar thermal modules according to the invention are particularly effective in absorbing focused solar radiation. Such focused solar radiation is provided, for example, by using heliostats, whereby the solar radiation from large areas can be concentrated onto the solar thermal modules of solar thermal receivers according to the invention.

The term “absorption area” in the sense of the present invention refers to the area of the solar thermal module which is adapted to be protected from the sun on its outside. heated by internal radiation and cooled on its inside by the heat transfer medium.

The term "tip of the absorption region" in the sense of the present invention refers to the end of the solar thermal module, which is opposite the inflow end of the solar thermal module, which is adapted so that the heat transfer medium flows into the solar thermal module through the inflow end.

The term “substantially convex outer surface of the absorption region” in the sense of the present invention means that the outer surface of the absorption region of the solar thermal module essentially has a convex shape. Preferably, only the connecting regions of the absorption regions arranged next to one another have non-convex components on .

According to a further aspect, the present invention relates to a solar thermal receiver comprising a plurality of solar thermal modules according to the invention, a heat transfer medium supply channel and a heat transfer medium discharge channel, the heat transfer medium supply channel being connected to the plurality of solar thermal modules, with a part of the heat transfer medium discharge channel being connected through an outer tube the large number of solar thermal modules is formed.

According to a further aspect, the present invention relates to a method for obtaining thermal energy from solar radiation, wherein solar radiation is absorbed by means of a large number of solar thermal modules according to the invention and the heat of which is transferred into a heat transfer medium, the heat transfer medium being guided from the large number of solar thermal modules into a heat transfer medium discharge channel , wherein the heat transfer medium is passed from the heat transfer medium discharge channel into at least one heat consumer and/or into at least one heat storage, wherein the heat transfer medium is passed from the at least one heat consumer and/or the at least one heat storage into the heat transfer medium supply channel, wherein the heat transfer medium is fed from the heat transfer medium supply channel again into the A large number of solar thermal modules are conducted.

To simplify the understanding of the invention, reference is made to the following detailed description and the attached figures. It should be understood that the following details of the embodiments should not be construed as limitations of the present invention. Instead, these represent preferred embodiments with particular advantages which may serve to better understand the present invention.

Fig. 1 represents a schematic view of a solar thermal tower system.

2 shows a sectional view through a single solar thermal module according to an embodiment of the present invention.

Fig. 3 shows a partial view of the vertical support structure of the solar thermal module with webs and bays according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module according to the invention shown in Figure 2.

4 shows a partial view for securing a screw head against rotation according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module shown in FIG. 2. According to one aspect, the present invention relates to a solar thermal module as described above.

According to further embodiments, it is preferred that the solar thermal module comprises a base plate B and a guide B, the base plate B and the guide B being suitable for forming lateral boundaries of the heat transfer medium discharge channel, the guide B having a base plate C is connected, the solar thermal module each having an articulated connection on a support surface between the base plate B and an outer tube and on a support surface between the guide B and the outer tube. It was found that with such embodiments of the solar thermal module according to the invention there is a vertical height offset in the heat transfer medium discharge channel between its rear wall as base plate B and its front wall as base plate C and the associated guide B in the area of the outer tube passing through can be balanced very effectively. The term “articulated connection” in the sense of the present invention is to be understood as a movable connection between at least two rigid bodies.

According to further embodiments, it is preferred that the solar thermal module has a vertical and horizontal inner support structure on the side illuminated by solar radiation, the inner support structure consisting of a base plate C and a guide B and a flange screwed thereto, the base plate C is mechanically decoupled from the guide B and the flange by guiding several webs of the base plate C distributed over the circumference into indentations in the guide B. It was found that for typical applications, noticeable mechanical stresses can build up in the solar thermal module. However, due to the structure described above, it is possible for there to be differences in temperature between the inner area of the support structure of the solar thermal module, which is not affected by solar radiation, even at very high temperatures is illuminated, and the outer area of the support structure of the solar thermal module, which is illuminated by solar radiation, only builds up low mechanical stresses in the solar thermal module.

According to further embodiments, it is preferred that the connection between the heat transfer medium supply channel and the inside of the tip of the absorption region consists of at least two pipes, the at least two pipes being connected to one another in an articulated manner. For example, in embodiments in which the attachment of the inner tube B to the inside of the tip of the absorption region is carried out in a rather delicate manner, it was observed that this structure achieves improved mechanical reliability of the solar thermal module.

According to further embodiments, it is preferred that a base plate A, an inner tube A and an inner tube B, preferably all components which are adapted to conduct the heat transfer medium inside the solar thermal module to the tip of the absorption area, consist of metallic materials and include a cap Cooling elements, a guide A, a flange, a base plate C with cooling elements, a guide B, an outer tube and a base plate B, preferably all components which are adapted to direct the heat transfer medium inside the solar thermal module away from the tip of the absorption area, made of ceramic materials consist. Such a structure has proven to be advantageous in order to minimize the mechanical stresses that occur as a result of the specific structure. The aforementioned combination of materials allows the thermal stresses to be kept low during operation of the solar thermal module in a very simple manner.

Furthermore, it has proven to be advantageous for typical applications if the inner tube B consists of at least one ceramic material. According to further embodiments, it is preferred that a base plate A and an inner tube A, preferably all components which are adapted to conduct the heat transfer medium inside the solar thermal module up to the direction of the tip of the absorption area consist of metallic materials and wherein an inner tube B, a cap with cooling elements, a guide A, a flange, a base plate C with cooling elements, a guide B, an outer tube and a base plate B, preferably all components which are adapted to direct the heat transfer medium inside the solar thermal module up to the tip of the absorption area and then away from the tip of the absorption area, consist of ceramic materials. Such a structure has proven to be advantageous in order to minimize the mechanical stresses that occur as a result of the specific structure and at the same time to provide increased resistance to thermal loads at this point in particular. This provides a particularly advantageous embodiment for applications subject to high thermal and mechanical stress.

According to further embodiments, it is preferred that there are a plurality of cooling elements on a base plate C, the cooling elements each adjoining a guide B at a small distance, the base plate C and the guide B forming a flow channel for the heat transfer medium, whereby the solar thermal module has a flow channel for the heat transfer medium, the surfaces of the base plate C and the guide B being geometrically designed in such a way that the free cross-sectional area of the flow channel continuously reduces in the direction of flow. The term “small distance” as stated above means that the tips of the cooling elements reach close to the surface of the guide B facing them, preferably as close as possible, but still retain a sufficiently large distance so that they are at the maximum possible Do not hit the guide B due to thermal expansion without causing impermissibly high pressure forces on the cooling elements. The maximum possible thermal expansion results consists of the maximum possible temperature differences of the base plate C, the cooling elements and the guide B.

According to further embodiments, it is preferred that there are screw connections distributed over the circumference inside the solar thermal module, each of which comprises a screw and a nut, the screw having a head, the head of the screw having at least one indentation in the longitudinal direction, preferably is provided all around with indentations, wherein next to the head of the screw, for example, there is a holding bay on the flange, and wherein the at least one indentation and the holding bay are suitable for receiving a locking pin. It was observed that a further improvement can be achieved in the structure of the solar thermal module according to the invention through such a security option. Typically, it is preferred that the solar thermal module also includes the locking pin on the screw arranged inside. In such embodiments, the screw connections also include a safety pin. Such a locking pin prevents accidental rotation of the screw in a simple and reliable manner.

According to further embodiments, it is preferred that the solar thermal module has a base plate C, wherein the base plate C has at least one attachment for adjacent solar thermal modules, the at least one attachment being adapted such that the heat transfer medium is guided along under the at least one attachment the heat transfer medium leaves the solar thermal module. Although the heat transfer medium already has a very high temperature when used at this point, it was found that the cooling effect that can be achieved here is very advantageous in typical applications. Particularly in the case of very strongly focused, intense solar radiation, the attachments of the neighboring solar thermal modules can Dule heat up very strongly, so that the cooling mentioned increases the area of application again without any noticeable additional effort.

According to further embodiments, it is preferred that the solar thermal module comprises a flange, an inner tube B, a guide A and a cap, wherein the inner tube B, the guide A and the cap are each fastened to the flange by means of Ba onett fasteners. In order to attach the inner tube B, the guide A and the cap to the flange using a bayonet lock, it is necessary to use a relatively complex structure of the solar thermal module. However, it has been shown that, in addition to the reliable fastening of the components, a particularly space-saving design is also possible in this way.

According to a further aspect, the present invention relates to a solar thermal receiver as described above.

According to a further aspect, the present invention relates to a method as described above.

According to further embodiments, it is preferred that the heat transfer medium is passed into at least one heat consumer, wherein the at least one heat consumer comprises at least one heat exchanger. Preferably, the at least one heat exchanger is a steam boiler and/or a preheater of a steam boiler. For example, such steam boilers and preheaters can be used in steam turbines. It was found that renewable energy can be used very efficiently for industrial applications, such as steam turbines in particular.

Figure 1 shows a schematic view of a solar thermal tower system 1. In the present case, the solar thermal tower system 1 comprises a heat transfer medium circuit 2, through which a heat transfer medium, which is presently gaseous, is passed, in which for example air. Integrated into the heat transfer medium circuit 2 are a compressor 3 that compresses the heat transfer medium, a solar thermal receiver 4 according to an embodiment of the present invention, which is supplied with the heat transfer medium compressed by the compressor 3 via a heat transfer medium supply channel 5, for example in the form of a pipeline, a heat transfer medium discharge channel 6, for example in the form of a pipeline, a heat consumer 8, for example in the form of a waste heat steam generator, and optionally a heat storage 7, which can be designed as a solid heat storage. From the heat consumer 8 and the heat storage 7, the heat transfer medium can then be directed back to the compressor 3 via a further connecting line 9, provided that the heat transfer medium circuit 2 is designed to be closed at this point.

The solar thermal tower system 1 further comprises a tower 10, in the upper region of which the solar thermal receiver 4 is arranged, and a plurality of heliostats 12 arranged on the floor 11, which are positioned around the tower 10 in the form of a ring or ring segment. The heliostats 12 are arranged and aligned in such a way that they reflect the solar radiation 13 and thus concentrate it as concentrated solar radiation 14 on the solar thermal receiver 4. For this purpose, the heliostats 12 are motor-tracked in at least two axes of the sun.

During operation of the solar thermal tower system 1, the gaseous heat transfer medium is compressed using the compressor 3 and fed to the solar thermal receiver 4 via the heat transfer medium supply channel 5. The heliostats 12 bundle and concentrate the solar radiation 14 onto the solar thermal receiver 4, through which the heat transfer medium flows. The heat transfer medium is heated to temperatures in the range of several hundred degrees Celsius. The heated heat transfer medium is then guided via the heat transfer medium discharge channel 6 in the direction of the heat consumer 8 or in the direction of the heat storage 7, where the heat medium releases its heat and is cooled down accordingly. The cooled heat transfer medium can then be directed back to the solar thermal receiver 4 via the connecting line 9 and the heat transfer medium supply channel 5, provided that the circuit between the heat consumer 8, heat storage 7 and compressor 3 is closed.

2 shows a portion of the solar thermal receiver 4 shown in FIG Base plate C 37 is aligned vertically so that the absorption region 30 faces the solar radiation 14 reflected from the ground at a suitable angle. Viewed from the direction of solar radiation 14, the absorption region 30 of the solar thermal module 15 is convex in its center and concave at its edges.

A solar thermal module 15 each comprises a channel-shaped continuation of the heat transfer medium supply channel 5 and the heat transfer medium discharge channel 6 in the interior of the solar thermal receiver 4 formed from many modules 15. The base plate A 31 forms the outer side of the continuation of the heat transfer medium supply channel 5. The inner side of this heat transfer medium supply channel 5 is omitted in the solar thermal receiver 4, provided that it is completely cylindrical or it is not shown in Figure 2 for a design that is not completely cylindrical, since it is irrelevant for the representation of the invention. The base plate B 33 and the base plate C 37 form the side walls of the heat transfer medium discharge channel 6 inside the solar thermal receiver 4, which becomes an annular channel when the design is completely cylindrical and forms a ring segment when the design is not completely cylindrical. The cold heat transfer medium enters from the heat transfer medium feed channel 5 into the inner tube A 48 of each individual solar thermal module 15, then flows through the inner tube B 47 and is thus directed to the inside of the tip of the absorption region 30. The outside of the absorption region 30 consists of the cap 44 and the base plate C 37, both of which are strongly heated by the concentrated solar radiation 14 and release the heat absorbed in the process to the heat transfer medium flowing along their insides. For this purpose, the cap 44 has a large number of cooling elements 45 on its inside, which adjoin the guide A 46 and the outside of the flange 40 at a short distance, while the base plate C 37 has a number of cooling elements 38 on its inside adjoin the guide B 36 at a short distance, which in its entirety forms the flow channel of an individual module 15 for heating the heat transfer medium. The heated heat transfer medium exits through a circumferential gap between base plate C 37 and guide B 36, whereby it reaches the common heat transfer medium discharge channel 6 of all solar thermal modules 15 connected in parallel.

For mechanical fastening, the inner tube A 48 is connected on its inlet side to a retaining nut 52, which biases a spring element 51. The compressive force of the spring element 51 is directed into the base plate A 31 via the sleeve 50. At the same time, the spring element 51 causes a tensile force on the inner tube A 48 via the retaining nut 52. On the exit side of the inner tube A 48, a collar located thereon introduces a corresponding pressure force into the outer tube 4 9. This compressive force is introduced from the outer tube 49 into the base plate B 33 with a collar located thereon via an articulated support surface 34, which is supported on the base plate A 31 via spacers 32. This closes the force flow generated by the pre-stressed spring element 51. This makes different thermal expansions of the inner tube A 48 and outer tube 49 possible without the s Mechanical cohesion of these two and the other components mentioned is lost.

The outer tube 49, which is held with the help of the spring force of the spring element 51, also has a collar on its side facing the absorption region 30, which can move in an articulated manner in the support surface 35 of the guide B 36. The articulated connection of the outer tube 49 with the base plate C 37 and with the other components in the absorption area 30 is achieved by the mentioned collar of the outer tube 49 being surrounded by the guide B 36 and the flange 40. The guide B 36 and the flange 40 are pulled together with several screw connections distributed over the circumference, each consisting of a screw 41 and a nut 39, so that they enclose the mentioned collar of the outer tube 49. The articulated support surfaces 34 and 35 make it possible to vertically offset the height of the two side walls of the heat transfer medium discharge channel 6.

The head of the screw 41 is positively secured against rotation with the help of the locking pin 42. A cover 43 located on the inner tube B 47 holds this locking pin 42 in position in a form-fitting manner and thus prevents it from accidentally falling out. The nut 39 is also positively secured against rotation in its respective holding bay of the guide B 36.

The inner tube B 47, the guide A 46 and the cap 44 are each attached to the flange 40 using bayonet fasteners.

During operation, the heat transfer medium is passed from the relatively cold heat transfer medium supply channel 5 through the inner tube A 48 and thus through the hot heat transfer medium discharge channel 6 in order to cool the absorption region 30 after flowing through the inner tube B 47. This cooling effect would be significantly reduced if the heat transfer medium was already flowing through the heat transfer medium as it flowed through the inner pipe A 48. dium removal channel 6 is very heated. Therefore, this bushing is formed in a clamshell form with the inner tube A 48 and the outer tube 49, which improves the efficiency of the solar thermal module 15.

It turned out that for the construction of the solar thermal modules 15 according to the invention, it is typically advantageous to take the thermal expansion of the materials into account. During operation, different temperatures arise in the components through which the cold heat transfer medium flows compared to the components around which the hot heat transfer medium flows. While metallic materials have a high thermal expansion, the thermal expansion of ceramic materials is low. Therefore, if metallic materials are exposed to a small temperature change and ceramic materials are subjected to a high temperature change, then similar absolute thermal expansions result for the metallic and ceramic components, which enables a construction with lower thermal stresses overall. Against this background, in particular the base plate A 31, the inner tube A 48 and the inner tube B 47 are made of metallic materials. Alternatively, the inner tube B 47 was made from at least one ceramic material, which is typically advantageous for many applications due to the higher thermal load capacity. In particular, the cap 44 with the cooling elements 45, the guide A 46, the flange 40, the base plate C 37 with the cooling elements 38, the guide B 36, the outer tube 49 and the base plate B 33 are also made of ceramic materials.

Nevertheless, 15 different thermal expansions of the various components remain during operation of the solar thermal module. Changes in length can be greatest between the cold inner tube A 48 and the hot outer tube 49. The spring element 51 compensates for such different changes in length without the cohesion of the solar thermal module 15 being lost. With several solar thermal modules 15 stacked one on top of the other, different vertical displacements of the hot base plate B 33 and the significantly hotter base plate C 37, which is heated directly by the solar radiation 14, can also result. Due to the articulated support surfaces 34 and 35, a vertical offset of the two base plates 33 and 37 is possible during operation of the system without impermissibly high thermal stresses arising in the connecting outer tube 49.

Although a vertical offset z of the two base plates 33 and 37 is made possible, this must not result in any leverage force which could have a destructive effect on the delicate transition from the inner tube B 47 to the guide A 4 6. Therefore, the supply of the cold heat transfer medium from the heat transfer medium supply channel 5 to the entry into the interior of the cap 44 is essentially carried out with two separate components, namely the inner tube A 48 and the inner tube B 47. The connection between these two inner tubes is made movable by the respective connection to the outer tube 49 and to the flange 40, because the outer tube 49 is movably mounted between the guide B 36 and the flange 40.

FIG. 3 shows a partial view of the vertical support structure of the solar thermal module 15 with webs and bays according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module according to the invention shown in FIG. 2. On the inside of the base plate C 37 there are several webs 70 distributed over the circumference, which protrude into indentations 71 of the guide B 36 and are each supported there with the aid of a seal 73. For illustrative purposes, FIG. 3 shows four webs 70 without the seals 73 on the right and four webs 70 with the seals 73 on the left. The bores 72 serve as a passage for the screw connection shown in FIG. 2, each consisting of screw 41 and nut 39, with the help of which the webs 70 are separated from the guide B 36 and The flange 40 is enclosed and thus held in position.

During operation of the solar thermal module 15, the external base plate C 37 has a significantly higher temperature than the internal guide B 36 and the flange 40. Due to the mechanical decoupling shown in FIG. 3, the base plate C 37 can expand unhindered to a greater extent than the guide B 36 and the flange 40, without the necessary mechanical connection between these three components being lost in the axial direction.

By separating the vertical and horizontal support structure on the side of the solar thermal module 15 facing the solar radiation 14 into the base plate C 37 and the screwed together components guide B 36 and flange 40, very different temperatures do not lead to unacceptably high thermal stresses in the radial direction direction, while the load-bearing function remains present in the axial direction.

Figure 4 shows a partial view for securing a screw head against rotation according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module shown in Figure 2. The head of the screw 41 is provided with indentations 91 all around in the longitudinal direction. Next to the head of the screw 41 there is a holding bay 90 on the flange 40. The form-fitting anti-twist protection of the screw 41 is achieved by inserting a locking pin 42 into the holding bay 90 and at the same time into an indentation 91 on the head of the screw 41.

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Solar thermal module (15) suitable for use as a component of a solar thermal receiver (4) for the absorption of solar radiation (14) for heating a heat transfer medium flowing inside the solar thermal module (15) with the following features, wherein the solar thermal module (15) has an absorption region (30) for solar radiation (14), the absorption region (30) having an outer surface, the outer surface of the absorption region (30) being substantially convex in the form of a cap (44), the absorption region (30) for Solar radiation (14) is impermeable, the solar thermal module (15) being suitable for being connected to a heat transfer medium supply channel (5), from which the heat transfer medium enters the solar thermal module (15), the solar thermal module (15) being adapted, that the supplied heat transfer medium flows through the solar thermal module (15) through at least one inner tube (47, 48), the heat transfer medium inside the solar thermal module (15) first being guided to the tip of the absorption region (30), the heat transfer medium being guided from the tip of the absorption region (30) inside the solar thermal module is guided along the remaining absorption region (30), the solar thermal module (15) being adapted so that the heat transfer medium leaves through an outlet into a heat transfer medium discharge channel (6), the at least one inner tube ( 47, 48) comprises an inner tube A (48), characterized in that a section of the inner tube A (48) is adapted to run through the heat transfer medium discharge channel (6), wherein the section of the inner tube A (48) is enclosed by an outer tube (49), the outer tube (49) being adapted to form part of the wall of the heat transfer medium discharge channel (6), the solar thermal module (15) having at least one spring element ( 51) in the flow of force between the inner tube A (48) and the outer tube (49), the at least one spring element (51) being adapted to compensate for different thermal expansion of the inner tube A (48) and of the outer tube (49), the at least one Spring element (51) has a spring force, which is transmitted in the inner tube A (48) as a tensile force and in the outer tube (49) as a compressive force. 2. Solar thermal module (15) according to claim 1 with the following features, wherein the solar thermal module comprises a base plate B (33) and a guide B (36), the base plate B (33) and the guide B (36) being suitable, to form lateral boundaries of the heat transfer medium discharge channel (6), the guide B (36) being connected to a base plate C (37), characterized in that the solar thermal module (15) each has an articulated connection on a support surface (34) between the base plate B (33) and an outer tube (49) and on a support surface (35) between guide B (36) and outer tube (49). 3. Solar thermal module (15) according to one of the preceding claims with the following features, wherein the solar thermal module (15) has a vertical and horizontal inner support structure on the side illuminated by the solar radiation (14), characterized in that the inner support structure consists of a Base plate C (37) and a guide B (36) and a flange (40) screwed to it, wherein the base plate C (37) is mechanically decoupled from the guide B (36) and the flange (40) by several webs (70) of the base plate C (37) distributed over the circumference in indentations (71) of the guide B (36 ). 4. Solar thermal module (15) according to one of the preceding claims, characterized in that the connection between the heat transfer medium supply channel (5) and the inside of the tip of the absorption area (30) consists of at least two pipes (48, 47), the at least two Pipes are connected to each other in an articulated manner. 5. Solar thermal module (15) according to one of the preceding claims, characterized in that a base plate A (31) and an inner tube A (48), preferably all components, which are adapted to the heat transfer medium inside the solar thermal module (15) up to to guide the vicinity of the tip of the absorption area (30), consist of metallic materials and wherein an inner tube B (47), a cap (44) with cooling elements (45), a guide A (46), a flange (40), a Base plate C (37) with cooling elements (38), a guide B (36), an outer tube (49) and a base plate B (33), preferably all components which are adapted to the heat transfer medium inside the solar thermal module (15) up to Tip of the absorption region (3) and away from the tip of the absorption region (30) consist of ceramic materials. 6. Solar thermal module (15) according to one of the preceding claims with the following features, wherein a plurality of cooling elements (38) are located on a base plate C (37), characterized in that the cooling elements (38) each adjoin a guide B (36) at a small distance, the base plate C (37) and the guide B (36) forming a flow channel for the heat transfer medium, the solar thermal module (15) forming a flow channel for the heat transfer medium, the surfaces of the base plate C (37) and the guide B (36) being geometrically designed in such a way that the free cross-sectional area of the flow channel continuously reduces in the direction of flow. 7. Solar thermal module (15) according to one of the preceding claims with the following features, wherein inside the solar thermal module (15) there are screw connections distributed over the circumference, each comprising a screw (41) and a nut (39), characterized that the screw has a head, the head of the screw (41) being provided with at least one indentation (91), preferably with indentations (91), in the longitudinal direction, in addition to the head of the screw (41), for example on the flange (40) a holding bay (90) is present, and wherein the at least one indentation (91) and the holding bay (90) are suitable for receiving a securing pin (42). 8. Solar thermal module (15) according to one of the preceding claims with the following features, characterized in that the solar thermal module (15) has a flange (40), an inner tube B (47), a guide A (46) and a cap (44 ), wherein the inner tube B (47), the guide A (46) and the cap (44) are each attached to the flange (40) by means of bayonet fasteners. 9. Solar thermal receiver (4) comprising a plurality of solar thermal modules (15) according to one of claims 1 to 8, a heat transfer medium supply channel (5) and a heat transfer medium discharge channel (6), wherein the heat transfer medium supply channel (5) is connected to the plurality of solar thermal modules (15), with a part of the heat transfer medium discharge channel (6) passing through an outer tube (49) of the plurality of solar thermal Modules (15) are formed. 10. A method for obtaining thermal energy from solar radiation, wherein solar radiation is absorbed by means of a plurality of solar thermal modules (15) according to one of claims 1 to 8 and transferred into a heat transfer medium, the heat transfer medium being selected from the plurality of solar thermal modules (15) into one Heat transfer medium discharge channel (6), the heat transfer medium being conducted from the heat transfer medium discharge channel (6) into at least one heat consumer (8) and/or into at least one heat storage (7), the heat transfer medium being passed from the at least one heat consumer (8) and/or the at least one heat storage device (7) is guided into the heat transfer medium supply channel (5), the heat transfer medium being fed from the heat transfer medium supply channel (5) again into the plurality of solar thermal modules (15). 11. The method according to claim 10, wherein the heat transfer medium is passed into at least one heat consumer (8), the heat consumer (8) comprising at least one heat exchanger, the heat exchanger being a heat exchanger of a steam boiler and / or a preheater of a steam boiler.