EP3877706A1

EP3877706A1 - Method for operating a receiver and receiver for carrying out the method

Info

Publication number: EP3877706A1
Application number: EP19806093.1A
Authority: EP
Inventors: Gianluca AMBROSETTI; Philipp GOOD
Original assignee: Synhelion SA; Eni SpA
Current assignee: Synhelion SA; Eni SpA
Priority date: 2018-11-08
Filing date: 2019-11-07
Publication date: 2021-09-15
Also published as: WO2020093179A1; AU2019374744A1; CH715527A2; US20220003458A1; CN113227670A; CL2021001196A1

Abstract

The receiver (25, 50, 100, 120) according to the invention is provided with a heating region (26) for heating a heat-carrying medium, having an optical opening (3) for sunlight and an absorber (27, 51) arranged in the path of the incident sunlight and absorbing said sunlight, and with a transport assembly (29) for transporting the medium through the heating region, wherein the absorber (27, 52) is designed as a black-body radiation assembly with reduced convection, and the transport assembly is designed for transporting a gas as the heat-carrying medium. In this way, the receiver can be designed to be simpler and more reliable.

Description

Procedure for operating a receiver and receiver for execution

of the procedure

The present invention relates to a method for operating a receiver and a receiver for executing the method according to the preamble of claims 1 and 14, and a manufacturing method for a receiver according to the preamble of claim 25.

Receivers are used in solar power plants. They collect the concentrated solar radiation and thereby heat a heat-transporting medium through which the heat obtained is used in a subsequent technical process, be it through conversion into mechanical work, for example by driving turbines, for the execution of heat Processes in industry or for heating, for example the district heating of inhabited areas.

In solar tower power stations, receivers designed as tube bundles are used, which are suitable for temperatures up to 600 ° C and concentrations of 600 suns. For higher temperatures, predominantly spatially trained receivers are used, which are designed for concentrations of 600 suns, 1000 suns or more. Such temperatures are usually above 600 ° C, range from 800 ° C to 1000 ° C and above, and can reach the range from 1200 ° C to 1500 ° C in the near future. Such receivers can also be used with dish concentrators, albeit on a smaller scale. In the present case, spatial receivers are referred to as receivers, the dimensions of which are comparatively large in all three dimensions, in contrast to tubular receivers which are used in conjunction with trough or channel collectors. Such tubular receivers have a dimension, the length, which is a multiple, in the region of ten or a hundred times or more, of the cross-sectional dimensions of the width or height. Receivers for trough collectors are not designed for the temperatures mentioned above, since the trough-shaped concentrator concentrates in two dimensions with respect to the receiver, but the field of heliostats in a tower power plant or a dish concentrator does so in three dimensions.

Such receivers are known to the person skilled in the art as volumetric receivers, which are also suitable for solar tower power plants, the temperatures required being such in receivers of more than 500 ° C, or more than 1000 ° C, for example up to 1200 ° C. However, the high operating temperatures lead to considerable design effort.

Volumetric receivers have an extensive (voluminous, hence the term "volumetric" receiver) absorber structure, which can consist, for example, of a voluminous wire mesh or an open-pored ceramic foam. The concentrated solar radiation then penetrates into the interior of the (voluminous) absorber structure and is absorbed there. The heat-transporting medium such as air or a suitable reaction partner for a subsequent reactor is passed through the open-porous absorber structure and thus absorbs heat by means of forced convection on the open-porous absorber structure. The absorber structure can also consist of a tubular structure, a staggered lattice structure or any structure with a large surface area which effects the convective heat transfer from the absorber structure to the heat-transporting medium when it flows through the absorber.

A volumetric receiver has become known, for example, from the REFOS project (Re ceiver for solar-hybrid gas turbine and combined cycle Systems; R. Buck, M. Abele, J. Kunberger, T. Denk, P. Heller and E. Lüpfert , in Journal de Physique IV France 9 (1999)), which is described in more detail below in connection with FIG. 1.

Such receivers have the disadvantage that the absorber structure is complex to manufacture and the flow through the absorber can become unstable, in particular due to a temperature distribution which is undesirable during operation.

Accordingly, it is the object of the present invention to provide an improved receiver.

This object is achieved by the method having the characterizing features of claim 1 and the characterizing features of claims 14 and 25.

Characterized in that according to the inventive method, the selected, heat-transporting gas is absorptive in the frequency bands of the infrared range, and the operating parameters If the meter is set in such a way that a significant part of the increase in heat takes place through absorption in the heat-transporting gas, a simplified concept of the receiver can be realized, since the heat transfer by convection is only reduced.

The fact that the absorption arrangement is designed as a black body radiation arrangement with reduced convection simplifies the design of the absorber, and thus the construction and operation of the receiver, since the absorber no longer convectively transports the heat introduced via the solar radiation to the heat via its depth Must deliver gas.

Preferred embodiments have the features of the dependent claims.

The invention is explained in more detail below with reference to the figures.

It shows:

La a receiver according to the prior art,

1b schematically shows a diagram with the temperature profile in the receiver of FIG.

2 schematically shows a receiver according to the present invention in longitudinal section,

3 schematically shows a further embodiment of the receiver according to the invention,

4 schematically shows a diagram with the temperature profile in the receiver of FIG. 2,

5 schematically shows a further embodiment of the receiver according to the invention,

6 schematically shows a cross section through yet another embodiment of the receiver according to the invention,

7a and 7b are diagrams with the temperature profile in a receiver according to the invention according to FIGS. 2 and 3, 8a to c diagrams with the efficiency and the temperature of the absorbent surface in a receiver according to the invention according to FIGS. 2 and 3.

9 schematically shows a further embodiment of the receiver according to the invention,

10 is a view of a further embodiment of the receiver according to the invention in the horizontal operating position,

11a shows a section through the annular space of the receiver of FIG. 10,

11b shows an enlarged detail from FIG. 11a,

12 shows the temperature distribution in the receiver according to FIGS. 10 to 11b according to a simulation

13 shows the steps of an operating method according to the invention for a receiver, and

14 shows the steps of a setting method for a receiver according to the invention.

Figure la shows an experimental arrangement for a volumetric receiver 1 according to the REFOS project, with a heating area 2 for heating a heat-transporting medium, here air, the opening 3 designed as a quartz window for the radiation of the sun or sunlight 4 and an arranged in the path of the incident radiation 4 behind the quartz window 3, this radiation 4 absorbing absorber 5. A trans port arrangement 6 for the transport of the heat-transporting medium through the heating region 2 has an inlet 7 in the embodiment shown, through which the medium enters the receiver 1 at an inlet temperature T and has an outlet 8 through which it leaves the outlet temperature T _out .

Via edge channels 9 of the transport arrangement 6, the air is conducted with the inlet temperature temperature T _in to the front side of the receiver 1, where it passes through suitably designed openings 10 into a distribution space 11 located in front of the absorber 5, is distributed and then flows through the absorber 5 , is thereby convectively heated, and finally reaches the temperature T _out in a collecting space 13 and from there into the outlet 8, through which it leaves the receiver 1. The quartz window 3 is arched towards the inside, so that the receiver 1 can be operated with increased pressure so that the heated air can be supplied under pressure to a downstream consumer, for example a turbine.

The absorber 5, which is constructed as a volumetric absorber and saves space by following the contour of the quartz window 3, has a number of layers of a fine wire mesh, into which the sunlight 4 can penetrate deeply, so that the absorber 5 heats up over its entire depth and thus through it Air flowing through is convectively heated to T _oiL . As mentioned above, a conventional absorber in other embodiments can be formed from an open porous ceramic foam or another arrangement with a very large surface area compared to the air volume in the absorber in order to achieve the required convective heat transfer.

An insulation 12 surrounds the receiver 1, to which a secondary concentrator, which is omitted to relieve the figure, is connected in front of its optical opening 3 and concentrates the flow of solar radiation 4 to the quartz window 3. To relieve the figure, a control for the receiver 1 and the transport arrangement 6 is also omitted, by means of which the operation of the receiver 1 or the supply and removal of air is suitably regulated, as is known to the person skilled in the art. An outlet temperature T _out of 800 ° C, with a ceramic absorber of 1000 ° C can be achieved by a receiver like the REFOS receiver shown.

FIG. 1b shows a diagram 15 with a temperature curve 16, which in connection with FIG. 1a shows schematically the temperature profile of the air flowing through the receiver 1. In section A from the inlet 7 to the end of the edge channels 9 there is a slight convective heating of the air from T, _h to Ti (part 17 of the temperature curve 16). In section B, during the passage of the air through the openings 10 in the absorber 5, there is a first, relevant and convective heating of Ti to T2 (part 18 of the temperature curve 16). In section C, ie in the distribution space 11, the air heats up absorptively, but only slightly, since air as a gas mixture contains, for example, a small amount of CO ₂ (or another gas) which absorbs in the infrared range, but is otherwise essentially transparent to infrared radiation (Part 19 of the temperature curve 16). Finally, in section D the air flows through the absorber 5, where it is convectively heated to the temperature T ₄ , which corresponds to the outlet temperature T _out (part 20 of the temperature curve 16). In section E, the air passes through the collecting space 13 into the outlet 8, which in turn results in a slight absorptive temperature increase due to the infrared-absorbing gas component. The temperature _jump from T to T _oiL is essentially convective, for example, according to diagram 15, the (realistic) ratio of the convective temperature increase to the absorptive temperature increase is greater than 5: 1.

Figure 2 shows schematically an embodiment of an inventive, designed as a spatial receiver receiver 25, with a heating region 26, which has an opening 3 for radiation from the sun, for example a quartz window, and a plate-shaped absorber 27 here, with between the quartz window 3 and the absorber 27 a He is a heating region forming absorption space 28 is provided, the medium from the heat transpor ting arrows shown from right to left, ie against the absorber 27, is flowed through. For this purpose, the transport device 29 has around the quartz window 3 arranged inlet connection 30 for heat-transporting medium, which lead into the absorption space 28, and a central outlet connection 31 behind the absorber 27. To relieve the figure here as in the following figures the isolation of the receiver omitted.

According to the invention, the absorber 27 is designed as a blackbody radiation arrangement, i.e. it has an arranged in the path of the incident sunlight or the incident sun radiation 4, this radiation absorbing surface 27 ', which is designed such that it heats up due to the incident on the surface 27' solar radiation 4 and then over its surface 27 'corresponding to infrared radiation in the absorber room 28.

Thus, the absorber 27 emits its heat output to a substantial extent in the form of infra-red radiation into the absorber space 28, where the heat-transporting medium flowing to it is already largely or predominantly absorptively heated with regard to T _oiL before it reaches it.

A real structure shines only approximately as the ideal black body does. In the present case, a “blackbody radiation arrangement” is understood to mean that the incident solar radiation 4 is absorbed as much as possible on the surface of the absorber. beers (so basically only little penetrates into the absorber, in contrast to the known volumetric absorbers), so that this surface heats up and thereby in the manner of a black body with the relevant high temperature in the absorber space 28, with other frequency spectrum compared to solar radiation. The predominant portion of the Schwarzköprer radiation emitted into the absorber chamber 28 is at temperatures of the absorber 27 to 2000 ° K (or also above) in the infrared range, ie, as mentioned, in lower frequencies than the visible light.

In other words, the absorber according to the invention is designed to be cooled via its blackbody radiation to such an extent that the ratio c can be achieved (see the description below).

An elaborate absorber structure, particularly for volumetric receivers, which is staggered in depth and which absorbs solar radiation or radiation from the sun over its depth accordingly also over its depth by at least partially scattering it inside and increasingly absorbing it after multiple reflections is thus eliminated. This also eliminates the complex thermal problems that frequently occur with such absorber structures. In addition, the simple geometry of the absorber chamber 28 provides a prerequisite for a flow of the heat-transporting medium flowing from the opening 3 to the opposite absorber 27, which medium continuously heats up against the absorber. The sun rays 4 preferably fall directly (i.e. without reflection on the walls of the absorber space 28) onto the absorber 27. The flow of the heat-transporting medium and sunlight falling directly on the absorber through the opening have a common direction. Despite the complex thermodynamic effects prevailing during operation, it is the case that a stratified heat distribution can be generated in the absorber chamber 28, the layers of which extend over the cross section of the absorber chamber 28.

This results in the constant heating of the heat-transporting medium towards the absorber 27, the coldest area of which lies at the opening 3, so that the loss of radiation from the opening 3 is optimally small. At the same time, the hottest area of the heat-transporting medium is located at the absorber 27, ie the furthest away from the opening 3, so that its (blackbody) infrared radiation is intercepted by the layers of the heat-transporting medium located between it and the opening 3, i.e. the Opening 3 is not reached or only reached to a minimum possible extent, which in turn increases the efficiency of the receiver according to the invention. Thanks to the medium which flows at least roughly uniformly against the absorber 27 across the cross section of the absorber chamber 28, the black body infrared radiation of the absorber 27 and the adjacent region of the heat-transporting medium result in no spreading of the hottest layer of the medium against the opening 3.

The absorber 27 is further preferably designed with little convection, i.e. For example, easily flowable, without increased convective properties are important for the heat exchange. This also eliminates the training for maximized convection of the medium flowing through, i.e. the structure necessary for the most efficient heat exchanger with a large surface area in comparison to the flowing volume of the heat-exchanging medium, which is complex and therefore costly to manufacture with high efficiency and which results in a considerable pressure drop in the flowing medium during operation, which in turn results for the Efficiency of the corresponding receiver is disadvantageous.

At this point, it should be noted that a certain convective heat transfer to the absorber 27 by contact with the heat-exchanging medium is of course inevitable, particularly in the embodiment shown in FIG. 2, since it forms a wall section of the absorption space 28 there. The corresponding convective heat transfer to the heat-transporting gas is, in itself, as well as any heat transfer, as far as welcome, as this does not require any design effort or, for example, increases the flow resistance - accordingly, the outlet temperature T _{out should} to a substantial or predominant extent (see also below) are based on absorption and thus enable a simplified structure of the receiver 25. The simplified structure of the absorber 27 opens, as mentioned above, the possibility for an inexpensive positioning (low-cost receiver for high temperatures) and also a more stable operation, for example from a thermal FH perspective (temperature distribution over the absorber 27), which leads to an improved Industrial suitability of the receiver leads.

According to the invention, there is a receiver with a heating area for the heating of a heat-transporting medium, which has an opening for the radiation of the sun, and an absorber arranged in the path of the incident radiation of the sun and absorbing it, with a transport arrangement for the transport of the medium through the heating area, with an absorption space for the outside of the absorber Heating of the heat-transporting medium is provided and the absorber is designed as a low-convection black body radiation arrangement and the transport arrangement for transporting a gas as a heat-transporting medium.

The absorber designed as a low-convection, black-body radiation arrangement is preferably designed for the through-flow of the heat-transporting gas and is more preferably located opposite the optical opening 3.

2, the absorber space 28 is preferably provided between the opening 3 for the radiation from the sun and the absorber 27, the ratio c being the ratio of the temperature increase (T ₃ - T2) by absorption of the radiation from the absorber 27 in this absorber space 28 to the total temperature increase (T ₄ - T2) by absorption and convection at the absorber 27 after the gas has passed through it. The gas has passed from the absorber 27 when it has either just passed through the absorber 27 and thus reached the collecting space 33, or when it has just been removed laterally at the location of the absorber 27 (for example through openings 92 "'or 93"'According to Figure 5), of course, both options can be provided simultaneously in a specific embodiment.

In a further embodiment, not shown in the figure, the collecting space 33, which is located on the rear side of the absorber 27, is designed as a further absorber space. In the case of an at least partially gas-tight absorber (see below), gas is conducted around the absorber to a rear of the absorber and then away from it.

Then the heat-transporting gas, which has already been absorptively and convectively heated, flows through this further absorption space and is additionally heated, absorptively and convectively, preferably according to the invention with a temperature ratio c> 0.3. Ultimately, this makes it possible to enlarge the radiating surface 27 'and thus optimize the absorptive heat transfer.

The heating area thus has two absorber rooms with a common absorber, the ratio c being provided for one or for both of the absorber rooms. According to the invention, an infrared-absorbing gas or gas mixture which absorbs in frequency bands of the infrared range is also used as the heat-transporting medium. Such gases are, for example, heteropolar gases, preferably CO2, water vapor, CH4, NH3, CO, SO2, SO3, HCl, NO, and NO2, or a mixture thereof, such as a mixture of water vapor and CO ₂ . When using such gases there is ultimately a usable or used greenhouse effect by the receiver 25, since these gases are highly transparent to the visible light, which thus essentially reaches the absorber 27, but little or hardly for the infrared radiation of the absorber are transparent, so that they warm up in front of the absorber 27 absorptively with respect to T _out to a considerable or predominant degree. It should be noted here that real gases do not absorb visible light or infrared radiation uniformly over all frequencies or are transparent to them, but above all in frequency bands specific for a particular gas. In addition, the absorption decreases with the distance from the radiation source. This speaks above with regard to the absorption or transparency of radiation of "highly transparent" or "little to hardly transparent".

It should also be noted that, of course, the radiation from the sun also has a portion of infrared frequency bands insofar as these reach the earth's surface through the atmosphere. Thanks to the design of the heating region 26 in such a way that it is little to hardly transparent for infrared frequencies this (comparatively small) portion as far as possible directly, without going through the absorber 27, so that according to the invention it is highly efficient for heating the heat-transporting fluid. This is in contrast to conventional receivers, in which the infrared portion of the solar radiation essentially heats up the absorber and is then predominantly released convectively to the heat-transporting fluid.

The absorber according to the invention can be designed as a perforated plate, preferably as a double perforated plate or as a simple, flat lattice structure. In the case of the perforated plate, a hole pattern is distributed over its extent, so that the heat-transporting gas can easily flow through, but sufficient or as much as possible of the surface of the perforated plate for absorption of the incident solar radiation and infrared reflection into the absorber space is. In addition, the hole pattern can be designed for easy flow, since there is no need for convection and reduced flow resistance is advantageous. The person skilled in the art can easily optimally determine the hole pattern in the specific case. Likewise in the case of a lattice structure or double perforated plate with two parallel ones Plates, in which case the holes of one plate are offset from one another in relation to those of the other plate, such that, despite the low-convection passage of the heat-exchanging gas, the absorption space faces the most continuous, radiant surface of the absorber. In this case the gas is led through the absorber. Alternatively, the absorber can also be made gas-tight, in which case the gas flows out of the absorber space 26 laterally, as shown for example in FIG. 5. Then the gas is led past the absorber. In a specific case, the person skilled in the art can provide a mixed form so that part of the gas flows through the absorber and part flows past it. The absorber then at least partially has a gas-tight surface and is preferably plate-shaped (a completely gas-tight surface is present when the gas is guided past the absorber).

A suitable material for the absorber has both a high degree of absorption of solar radiation and a high emissivity of infrared radiation, which - if necessary - with suitable texturing of the surface 27 'such as V-grooves, pyramids protruding into the surface or protruding, or other radiation traps can also be increased. In addition, high temperature (change) and corrosion resistance (e.g. against oxidation by water vapor or C02 at high temperatures) are required. Suitable materials are floch temperature ceramics such as silicon carbide (SiC) as well as fire-resistant building materials, which the person skilled in the art can select in particular in view of the temperature range provided.

In a further embodiment, modified from the arrangement in FIG. 2, which is shown schematically in FIG. 3, the inlet connections 30 (FIG. 2) are not arranged around the quartz window 3, but in the direction of the incident solar radiation 4 behind the quartz window 3 or the opening for solar radiation. As a result, the corresponding lines for the heat-transporting gas are not in the plane of the quartz window 3, but at least immediately behind, i.e. not on the surface of the receiver 25 facing the incident light. A corresponding shielding against the light is thus omitted, the opening 3 being able to be dimensioned precisely to the cross section of the incident, concentrated light.

The result is a receiver according to the invention with a heating area for the heating of a heat-transporting medium which has an opening for the radiation of the Sun, and a arranged in the path of the incident radiation of the sun, this absorbing absorber has, with a transport arrangement for transporting the medium through the heating area, wherein an absorber space for heating the heat-transporting medium is further provided, one end of which the opening for the radiation of the sun and its other end is formed by the absorber lying opposite the opening, such that the sun's radiation entering through the opening essentially falls completely on the absorber, and the absorber acts as a radiation arrangement acting in the absorber space and the transport arrangement for the transport of a gas is designed as a heat-transporting medium, and this in the area of the opening, but in the direction of the incident radiation behind the opening, feeds the absorber chamber and (only) in the region of the absorber from the absorber chamber, such that in operation there s heat-transporting medium completely crosses the absorber space in a direction corresponding to the incident solar radiation from one end with the opening to the other end with the absorber, and the heat-transporting medium is essentially a gas that absorbs in frequency bands of the infrared range and that with the Absorber interacting absorber space is dimensioned such that, during operation, the ratio c of the temperature increase (T ₃ - T2) of the heat-absorbing gas absorbing in frequency bands of the infrared range by absorption in the absorber space compared to the temperature increase (T ₄ - T ₂ ) due to the absorption and the convection at the absorber is> 0.3.

In the specific case, the receiver according to the invention can be designed in such a way that the temperature increases during transport through the heating area by absorption of the radiation from the absorber in such a way that the ratio c of the temperature increase (T ₃ - T ₂ ) by Absorption of the radiation from the absorber compared to the total temperature increase (T ₄ - T ₂ ) due to the absorption of the radiation from the absorber and convection at the absorber is> 0.3, but is particularly preferred up to> 0.8 (see the description below) .

This arrangement makes it possible, inter alia, to generate a stable temperature distribution during operation, with the temperature increasing steadily towards the absorber 27, the temperature distribution in a cross section of the absorber space also not changing significantly over time. Constantly rising temperature against the absorber means that the layer of the heat-transporting gas adjacent to the opening or to the quartz window 3 is the has the lowest temperature and thus generates the lowest heat reflection through the quartz window 3, which contributes to the high efficiency of the receiver according to the invention. The same temperature distribution over the cross section of the absorber space allows the outlet port 31 to be provided at an optimal location, for example at the location of the highest temperature of the heat-transporting medium, which is not, as shown in FIG. 2 by way of example, arranged centrally on the longitudinal axis of the receiver have to be. For example, in a receiver 25 arranged obliquely on a solar tower in the absorber chamber 28, convection currents can occur in the heat-transporting medium, so that the outlet connection is not to be arranged centrally, but offset towards the top, see FIG. see also the description for Figures 9 and 10 below.

In any case, the arrangement according to the invention enables a constant, stable temperature distribution in the receiver 25 with optimally low retroreflection through the quartz window 3. FIG. 4 shows a diagram 40 with a temperature curve 41, which in connection with FIG. 2 or FIG shows the receiver 25 flowing gas.

In section F, part 42 of the temperature curve shows the heating of the infrared-absorbing, heat-transporting gas from T _in to Ti, in the event that, in the embodiment of the receiver 25 shown in FIG. 2, the infrared-absorbing gas as in the receiver 1 the air (FIG. 1) is also to be transported along the absorption space 28 to the end face (which is, however, not mandatory). In section G there is a slight convective heating of the air from Ti to T2 (part 43 of the temperature curve 41) due to the passage of the gas through the inlet connection 30.

In section H the infrared absorbing gas flows through the absorption space 28 and it heats up absorptively by the infrared radiation 32 of the absorber 27 (here with the infrared portion of the solar radiation) from T2 to T3 (part 44 of the temperature curve 41) before it cuts off I flows through it and heats up convectively from T3 to T4 (part 45 of temperature curve 41). Finally, there is a further absorptive heating of the infrared absorbing gas in the section K from T ₄ to the outlet temperature T _out (part 46 of the temperature curve 41) while the gas is in the collecting space 33 and against the outlet nozzle 31 flows. According to the invention, the jump in temperature from T _in to T _out is largely absorptive. It follows from the illustration in FIGS. 2 and 3 that the transport arrangement of the receiver preferably has an absorption space 28 in the flow direction upstream and a further absorption space (here designed as a collection space 33) in the flow direction behind the absorber 27.

In a specific case, the person skilled in the art determines the operating parameters, generally starting from the desired or necessary outlet temperature T _out and the inlet temperature T given by the use of the heat from the receiver. Furthermore, he selects the infrared absorbing gas or gas mixture suitable in the specific case and defines the flow rate in the absorption space 28 (which in turn may depend on the current sun radiation). Such and other operating parameters resulting in the specific case can depend on one another, with the result that the absorptive increase in the temperature from T to T in section F1 of FIG. 3, ie in the absorption space 28, in the specific case depending on the larger or smaller fails.

The applicant has found that the advantages according to the invention have a relevant effect even at a ratio c of> 0.3, where

i.e. indicates the ratio between the absorptive and the total absorptive and convective heating of the heat-transporting gas when the gas has flowed towards an absorber 27 radiating in the infrared region and then through it (or along it to an outlet), i.e. happened to this. By suitable operation with the selected operating parameters, in other words by a suitable design of the control of the receiver 25, the person skilled in the art can achieve the value according to the invention of c> 0.3 in the specific case.

As mentioned, the person skilled in the art can, in the specific case, have the ratio c> 0.3 on the absorption of only the absorber radiation 32.55 or on the absorption of the absorber radiation, including the absorption of the infrared portion of the radiation through the absorption space 28, 57 (FIGS. 2 and 5) 4) refer to ongoing solar radiation 4. It results that according to the invention a gas which absorbs in frequency bands of the infrared range is provided as the heat-transporting medium. Furthermore, it is according to the invention that an absorption space interacting with the absorber is dimensioned such that in operation the ratio c of the absorptive temperature increase (T ₃ - T2) of a heat-transporting gas absorbing in frequency bands of the infrared range in the absorption chamber compared to the total temperature increase ( T ₄ - T ₂ ) by absorption and convection at the absorber> 0.3.

The heat-exchanging gas preferably flows through an absorber zone (absorption space 28) against an absorber (absorber 27), it being absorbed in the absorber zone and also convectively heated by the absorber. A receiver can be structured in several stages, i.e. Gradually heat up heat-transporting medium. According to the invention, at least one stage for an absorptive / convective heating with the ratio c of> 0.3 is then formed.

The heating region then preferably has two absorption spaces, the ratio nis c being provided for one or for both of the absorption spaces in conjunction with the absorber.

For a high efficiency of the receiver according to the invention, it is also decisive that the amount of heat radiated by the absorber is absorbed as far as possible by the gas transporting gas in the absorption space (and, for example, does not penetrate the gas and escapes from the receiver through the opening for solar radiation as reflection). A determining parameter here is the absorptivity a of the heat-transporting gas, which can be measured by experiments, calculated from spectral line values from molecular spectroscopic databases (eg FIITEMP2010), or can also be determined approximately from emissivity diagrams according to the rule of the fleet. If, in one embodiment, the distance F1 between the absorber and the opening has such a distance under the current operating conditions of the receivers that 60% or more of the heat output radiated by the absorber is absorbed by the heat-transporting gas in this spatial region, the efficiency of the Receiver that is designed to absorb the absorber heat. A flea in the space area mentioned is particularly preferred such that 80% or more, particularly preferably 90% or more, of the radiated thermal output of the absorber is absorbed by the heat-transporting gas. It should be noted here that the absorber space certainly has an opening for the radiation from the sun and an absorber acting in it via its blackbody radiation, ge according to FIGS. 2 to 4 preferably the absorber opposite the opening. In principle, however, the absorber space can not be cylindrical, but can be configured as desired, for example with a jumping side wall, so that the opening is smaller than the surface of the absorber, which is advantageous in view of the undesired reflection. In such a case, the radiation is concentrated in the opening by a concentrator and diverts after the opening in such a way that the entire and larger absorber surface is illuminated. Then the absorber room may not have a height under the protruding walls, but under the opening such that there is an absorption in the above-mentioned degree in the affected area (where this height is present).

Since the absorptivity depends on the type of gas, its pressure and the temperature of the radiating absorber surface and that of the gas itself (Hottel rule), the person skilled in the art can determine the height depending on the parameters determining the absorption: as mentioned, these are the types of the gas, its operating pressure, its temperature and the temperature of the absorber surface during operation, which in this respect determine an operating state of the receiver.

The result is a preferred embodiment of the receiver according to the invention, in which the absorption space has a height above the absorber such that, when the receiver is in an operating state, 60% or more, preferably 80% or more, very particularly preferably 90% or in this area more of the radiated heat output of the absorber is absorbed by the heat-transporting gas.

FIG. 5 shows a further embodiment of the receiver according to the invention. A section through a receiver 50 is shown, which corresponds to the receiver 25 of FIG. 2, but the absorber 51, with its absorbent surface 51 'facing the optical opening 3, has a preferably plate-shaped section 54 which projects into the absorber space 57 and has a section extends in the middle of the absorber chamber 57 against the opening 3 and which is oriented essentially parallel to the flow direction of the infrared-absorbing, heat-exchanging gas indicated by the arrows. The section 54 essentially absorbs infrared radiation emitted by the absorbing surface 51 ', insofar as this has not yet been absorbed by the gas flowing along it, that is to say in particular radiation in those frequency bands for which the gas is less absorbent. As a result, it heats up and in turn represents a black-body radiation arrangement which radiates the frequency spectrum corresponding to the temperature of section 54 and heats the gas flowing past in turn absorptively. This results in an improved use of those frequencies of radiation 55 which are only slightly absorbed by the gas, since these frequencies introduce heat into section 54, which in turn radiates in all (infrared) frequencies. From section 54 represents a secondary absorber.

Such an arrangement can be implemented in larger dimensions, for example with a diameter of the absorber surface 51 'of 15.96 m and a length of the absorption space 53 (absorber surface 51' to optical opening 3) of 15.96 m. The receiver 50 is then suitable for recording the flow of a large number (or all) of fleliostats in a tower power plant. The result is that the receiver 50 has an absorption space 57 and the absorber 51 projects into this space with a section or secondary absorber 54, which is preferably plate-shaped.

In a further embodiment, not shown in the figure, a glass wall (borosilicate glass), for example transparent for the visible spectrum of sunlight, can be provided as secondary absorber, which is approximately parallel in the middle between the absorber surface 51 'and the optical opening 3 (FIG. 4) is arranged to the absorber surface 51 'and has passages, for example in the manner of a perforated plate, for the heat-transporting gas. Again, the glass wall is heated by the infrared radiation of the absorber surface 51 ', or by its frequency components which have not yet been absorbed by the gas, and even in the manner of the black body radiates in both directions, namely both against the optical opening and against the absorber. The person skilled in the art can design the glass plate in such a way that for the section of the absorption space between the glass plate and the optical opening and the glass plate assigned to it and also for the section of the absorption space between the glass plate and the absorber with the absorber assigned to it the ratio c of> 0.3 is reached. According to the invention, there is a receiver that reduces another one as a blackbody radiation arrangement Convection trained secondary absorber in an in front of the absorber Absorpti onsraum, which is arranged and designed such that it can be heated by the infrared radiation of the absorber.

Fig. 6 shows schematically a cross section through a further embodiment of a receiver in the manner of that of Figure 2. The sun rays 4 fall through a window, for example quartz glass 3 on the absorber 27, the radiant surface 27 'flowing through in the absorption chamber 26 Gas heats, the temperature of which increases from window 3 to absorber 27. Accordingly, the gas can be removed via openings 91 to 91 "'' in the cylindrical wall of the receiver 90 at predetermined, different temperatures below the operating temperature of the heat-transporting fluid, but the main flow of the heat-transporting fluid is still the same in the region of the absorber is taken from the absorption space 26 at operating temperature, the arrows indicate the direction of flow of the heat-transporting gas, the arrows at openings 91 to 91 '"being drawn in correspondingly longer as the temperature rises. Alternatively - or together with the openings 91 to 91 '", a line 93 protruding into the absorption space 26 can be provided for the gas, which then has openings 92 to 92'" in the gas at the location of the openings 92 to 92 '" This is particularly advantageous if a downstream process at different temperature levels is supplied with heat by the receiver 90. From this process, heat-transporting gas can also be returned to the receiver at different temperatures that further preferably in the area of the openings 91 to 91 '"and 92 to 92'" further supply lines for the heat-transporting gas are provided in the absorption space 26 of the receiver 90 (which are omitted here to relieve the figure).

The result is a receiver in which the transport arrangement has one or more lines 91 to 91 '"and 92 to 92'" connected to an absorber space 26 for heat transport of the gas, which are arranged such that gas which has been partially heated is removed from the absorber space 26 / or partially heated gas can be supplied at a location at which the temperature of the gas in the absorber space 26 essentially corresponds to the temperature of the partially heated, supplied gas. Such supply and discharge lines for partially heated gas can be provided on an absorptive receiver according to the invention without having to modify its layout, in particular the absorber 27 - these lines can also be used or shut down without it due to the different heat transfer a constructive modification is required.

The applicant has found that a temperature ratio c> 0.5 is particularly advantageous when partially heated gas is used, for example when the partially heated gas is in the range of at an inlet temperature T _m of 1000 K and an outlet temperature T _out of 1800 K. 1400 K, that is to say half the temperature difference, is: the temperature layer T = 1400 K in the absorber chamber 26 is still in the purely absorptive range and is accordingly easily accessible, in FIG. 5 through the openings 91 to 91 "or 92 to 92".

FIGS. 7a and 7b and 8a and 8b show various operating parameters in a receiver according to FIG. 2 according to a mathematical modeling of the receiver 25 from FIG. 2 by the applicant. The system has been modeled using the most precise method available today, namely "spectral line-by-line (LBL) photon Monte Carlo ray tracing", the absorption coefficients coming from the HITEMP 2010 Spectroscopic Database. A receiver is modeled, whose absorption space has a diameter of 15.96 m and a flea of 15.96 and the opening 3 has a diameter of 11.28 m. This results in an area of the absorbent surface 27 'of 200 m ² and an area of the opening 3 of 100 m2. Water vapor was assumed to be the heat-transporting medium, at a pressure of 1 bar, without a window in the opening 3. The radiation flow at the opening 3 is 200 kW / m ² and at the absorbing surface is 27,600 kW / m ² (which is opposite the Opening 3 has twice the area). The absorbent surface 27 'was assumed to be a radiant black body and, in contrast to FIG. 2, with a continuous, flat and smooth surface, so that the heat-transporting medium in the manner shown in FIG. 5 through openings 91'"at the level of the absorber 27 is guided laterally out of the absorber space 26.

FIGS. 7a and 7b show, using diagrams 60 and 65, the temperature profile during operation of the receiver 20 (FIG. 2) along its longitudinal axis, starting from the opening 3: the temperature in Kelvin is plotted on the vertical axis and on the horizontal axis the distance from the opening 3. Diagram 60, FIG. 6a, shows a process with an inlet temperature T _m of 100,000 K and an outlet temperature T _out of 400 K. Diagram 65, FIG. 6b, also shows a process an inlet temperature T of 1,000 K, but an outlet temperature T _out of 800 K.

Because of the walls that heat up during operation, there is a temperature distribution in the heat-transporting medium (here water vapor) with an increased temperature at the edge of the absorber space 26, so that at a certain cross section in the absorber space 26 at the edge (on the wall) (temperature curves 61 and 66, respectively) ) the highest and in the middle, at the location of the axis of the cylindrical absorber chamber 26, the lowest temperatures (temperature curve 62 or 67) are present. The temperature curves 63 and 68 show the average temperature of the water vapor in the respective cross section of the absorber space 26.

FIGS. 7a and 7b show, along with a proof-of-concept for an absorptive receiver according to FIGS. 2 and 3, the possible design of such a receiver according to FIG. 6.

FIG. 8a shows a diagram 70 for the efficiency of the receiver 20 (FIG. 2). The output temperature T _{out is} plotted on the horizontal axis, a constant input temperature T _in of 100,000 K being assumed. Curve 71 shows the efficiency of receiver 20 as a function of the initial temperature T _out . The reduction in efficiency against higher temperatures T _{out can} be explained by the increased (loss) retroreflection from opening 3 due to the higher temperatures - despite the constant input temperature Ti _n of 100,000 K, since part of the retroreflection from the Inside the absorber room (with elevated temperatures). The concept of the absorptive receiver accordingly has an efficiency level that is equal to that of conventional convective receivers or even better with an increasing output temperature Tout.

FIG. 8b shows a diagram 75 for the temperature of the absorbent surface 27 'as a function of the starting temperature T _out . Again there is a temperature distribution with higher temperatures at the edge and a minimum temperature at the location of the axis of the cylindrical absorber space 26: curve 76 shows the temperature at the edge of the absorbing surface 27 'and curve 77 the temperature in the middle thereof. Curve 78 shows their average temperature. The temperature difference to the absorbing surface 27 ′, which becomes smaller with a higher T _out, can be explained by the fact that the energy radiation of the black body increases with the fourth power of its temperature - with a relatively small temperature increase (here by 300 K), the heat-transporting medium becomes massively higher heated (here around 1000 K). The concept of the absorptive receiver therefore has considerable flexibility with regard to the intended temperature T _out : an absorber suitable for high temperatures can equally be used for different temperatures T _out , which is not the case with the convective absorbers of the prior art and that Concept of apsorptive low-cost-high-temperature receiver supported.

The ratios shown in FIGS. 8a, b and 8a, b also apply, according to the modeling used, to a receiver 20 (FIG. 2) with smaller dimensions but increased pressure in the heat-transporting medium.

FIG. 8 c shows a diagram 80 for the efficiency of the receiver 20 (FIG. 2), but with a window in the opening 3 and for different dimensions. The degree of efficiency for the large dimensions of the receiver 20 can be seen in accordance with the description of FIGS. 6a, b and 7a, b, s. curve 82. The efficiency can also be seen for small dimensions (diameter and height of the absorber chamber 26 = 1.596 m, diameter of the window in the opening 3 = 1.128, corresponding to 1 m ² ), with a pressure in the heat transporting the gas from 10 bar, see curve 81. The somewhat lower efficiency compared to FIG. 7a is explained by the reduced flow due to the window on the absorbent surface of 554.4 kW / m ² instead of 600 kW / m ² .

The diagrams according to FIGS. 8a to c also apply to a receiver according to FIG. 3.

In Figure 3, the receiver 100 is shown with an axis 103, which is arranged vertically, in which case the radiation from a heliostat field is directed vertically downwards onto the receiver 100 located near the ground via mirrors arranged in the solar tower, such an arrangement is known to the person skilled in the art known as "beam down". (Conversely, the radiation from the heliostat field can also be directed vertically upwards via mirrors or by the heliostats themselves, in which case the receiver 100 is located on the top of the solar tower.) The heat-transporting medium is now, as mentioned above, in contrast to the embodiment tion form according to Figure 2 not through nozzles or openings 30 in the plane of the opening (or a window) 3 for the radiation 4 from the sun to the absorber chamber 28, but in the direction of the incident radiation 4 behind the opening 3 for this radiation. It is thereby achieved that the corresponding supply lines 102 for heat-transporting medium can be arranged further away from the opening 3 and at the same time can be easily protected. The nozzles or feed points 30 for heat-transporting medium according to FIG. 2 located near the opening 3 are disadvantageously endangered, in particular in the case of incorrect alignment of the fleliostats, and must be designed to be highly temperature-safe for a very high energy input, which is the simplicity of the invention - Contrary to the receivers according to the design effort.

Furthermore, in particular in a vertically downwardly oriented receiver 100, the flow of the fluid transported through the absorber chamber 28 is formed quite uniformly and thus a clear temperature stratification results over the fleas of the absorber chamber 28. In the case of a "beam-down" arrangement, it can be useful in the specific case to provide a swirl in the fluid according to FIGS. 9 to 12 in addition to a sufficiently high flow rate of the heat-transporting fluid against the absorber

As mentioned above, designs are also used in a solar tower power plant, for example, in which the receiver is arranged at the top of the tower and is oriented obliquely downward in order to directly absorb the radiation from the fleliostat field. The oblique orientation results in corresponding obliquely arranged temperature layers, which can produce a convection flow in the heat-transporting fluid, which disrupts the temperature layer and thus also the desired uniform temperature in the region of the absorber 27.

According to the invention, it is therefore provided according to the embodiment according to FIG. 9 to supply the heat-transporting fluid tangentially to its transport direction given in the absorber chamber 28, so that the gas conducted in the heating region or in the absorber chamber 28 in the transport direction against the absorber 27 additionally by one to the transport direction parallel axis 103 rotates.

Figure 9 shows schematically a view of an obliquely arranged receiver 110 on the side of its opening 3 for the radiation of the sun, tangential to the axis 103 arranged supply lines 104 for the heat-transporting medium can be seen, which generate a rotation of the medium or a swirl in the medium flowing against the absorber 27. The absorber 27 can be seen through the opening or the quartz window 3 in the figure, with the flow path of the medium through the absorber (or past it) not being drawn in, in order to relieve the figure, but only in broken lines an outlet connection 106, from which chem the medium leaves the receiver 110. The outlet nozzle is preferably arranged slightly eccentrically upwards, which in combination with the swirl of the flowing medium results in a stable temperature in the heat-transporting medium at the location of the outlet nozzle 106.

As a result, the transport arrangement is preferably designed such that, during operation, the heat-transporting medium at least partially has a swirl around an axis 127 of the absorber space parallel to the transport direction during the passage through the absorber space, the transport arrangement preferably providing inlet openings for the absorber space the medium has, which are aligned tangentially with respect to the axis of the absorber chamber in the same direction of swirl.

It should be noted at this point that the rotation of the flow or the swirl can also be generated by baffles in the absorber space 28, which is preferably achieved in its cold area thanks to the defined temperature stratification and thus only insignificantly increases the effort for the receiver according to the invention .

Figures 10 to 12 show details of a receiver 120, which is designed for high efficiency even with oblique or horizontal positioning. FIG. 10 shows a view from the outside of the receiver 120, FIGS. 11a and b show a cross section through it, and FIG. 12 shows the stratified temperature distribution in its absorption space 28 according to a simulation by the applicant. To relieve the figures, the isolation of the receiver 120 and its supporting outer structure, which the person skilled in the art can easily design in the specific case, are again omitted.

FIG. 10 shows the receiver 120 with its absorption space 28, the collecting space 33 and the outlet connection 121 (see also the illustration in FIG. 2). A supply arrangement 122 for cold (T _in ) heat-transporting fluid, which is a component of the transport arrangement 29 (FIG. 2), can also be seen. The feed arrangement 122 has an annular space 123, open into the supply lines 124 for heat-transporting fluid, see. the arrows 125, where, with the fluid flowing into the receiver 120 via the annular space 123, crosses the absorber space 28 in a main flow direction parallel to the axis 127, it heats up and finally leaves the receiver 120 again at the temperature T _out via the collecting space 33 and outlet connection 121 ( Arrows 126). Sun rays 4 pass through an opening in the figure from the annular space 123 or through a window 3 into the absorption space 28 up to the inside of the collecting space 33, the inner wall of which in the illustrated embodiment is designed as an absorber for the solar radiation. As he mentions in the description of FIG. 9, in the embodiment shown the outlet connection 121 is arranged upwards.

FIG. 11a shows the annular space 123 in section, the sectional plane again passing through an axis 127 running longitudinally through the absorption space 28 and the feed lines 124 (see also FIG. 10). The annular space 123 is shown to scale, as is the closing area of the absorption space 28 and the position of the opening 3 or a window 3 for the radiation from the sun. As mentioned above, however, the insulation and the supporting structure are omitted, here in particular that for the window 3 and the annular space 123. Also shown are the supply lines 124 for the heat-transporting fluid arranged upstream or on the inlet side. Downstream or on the outlet side, the annular space 123 is divided into an outer annular channel 132 with an annular outlet slot 130 and an inner ring channel 133 with an annular outlet slot 131. The outer channel 132 runs coaxially to the axis 127 of the absorption space 28 and adjacent to its wall 138, the inner channel 133 has a frustoconical configuration and is directed obliquely towards the interior of the absorption space 28. As a result, 138 zones with reduced flow towards the absorber are formed in the area of the wall only in a reduced manner or to an extent that is no longer relevant, although in spite of the somewhat hotter walls (see the diagrams in FIGS. 7 and 8), finally in front of the absorber A homogeneous temperature layer results over the cross section of the absorption space 28 (see also FIG. 12). For this reason, a flow component from the outer channel 132 runs particularly preferably parallel to the wall 138, before the angle of which to the wall 130 is less than or equal to 5 degrees. A positive effect can still be achieved at an angle less than or equal to 10 degrees or 15 degrees. The ring channels 132, 133 are provided with baffles 134, 135 (see FIG. 11b), so that openings for the heat-transporting medium are formed in the outlet slots 130, 131 and additionally impart a flow component tangential to the axis 127. It therefore enters the absorption space 28 in a directional flow and, in addition to the main flow direction parallel to the axis 127, has a (twist) flow direction tangential to the axis 127. This results in the spiral-shaped flow lines 136 and 137 shown as an example in the figure. As a result, a disturbance in the temperature stratification in the receiver 120 by, for example, temperature-related convection currents can be suppressed, in particular with an oblique or horizontal orientation.

Figure 11b shows an enlarged section of Figure 11a to clarify the conditions. In particular, the baffles 134 'to 134 "' and the components of the directional flow 136, namely those in the direction of the main flow 141 and the tan potential component 142, can be seen.

The result is a receiver in which the transport arrangement has openings for the heat-transporting medium leading into the absorber space, which are arranged adjacent to a wall 138 of the absorption space 28 and which in the main flow direction contain a flow component of the fluid flowing into the absorption space 28 with a Inclination to wall 138 less than 15 degrees, preferably equal to or less than 5 degrees. According to the applicant's knowledge, such small angles are necessary in order to avoid, in the region of the wall 138, zones of reduced flow velocity toward the absorber which are relevant for the efficiency of the absorber.

There is also a receiver in which the transport arrangement has openings for the heat-transporting medium which lead into the absorber space and which generates a flow component tangential to an axis 127 of the absorption space 28 of the fluid flowing into the absorption space 28.

Finally, there is a method for operating a receiver, in which the infrared-absorbing gas is set into rotation in an absorption space (28, 53) of the heating region (26), such that there is a swirl in the absorption space by one in the transport direction or Main flow direction, extending axis (127). FIG. 12 shows the temperature distribution according to a CFD simulation by the applicant in the absorption space 28 of the receiver 120 with the following boundary conditions:

^■ Diameter of the absorption space 0.8 m, pressure in the absorption space = 1 bar

^■ T _in = 800 ° K, mass flow of the heat-transporting fluid = 0.045 kg / s

^■ Solar radiation power through the transparent opening 3 = 250 kW, diameter of the opening: 0.6 m

^■ Heat-transporting fluid: water vapor

^■ Spectral radiation behavior of water vapor modeled with weighted sum of gray gases (WSGG) model and radiation solved with the discrete ordinates (DO) method

^■ Black walls, e _waii = 1

^■ Gravity pointing vertically downwards (horizontal receiver)

^■ Angle of the fluid flowing into the absorption space: 45 degrees

The angle of the inflowing fluid in the ring channel 132 is the angle between the directed flow 136 and the direction of the fluff flow 141 from FIG. 11b. The annular channel 133, as mentioned above, has a frustoconical configuration, i.e. its downstream end is circular. The angle of the fluid flowing into the absorption space from it is analogous to the angle of its direction of flow to a tangent to this circle.

A simplified geometry in the area between the optical opening 3 and the walls 138 of the absorption space 28 has been assumed for the simulation: the space between the outlet slots 130 and 131 (FIGS. 11a and b) has been replaced by a frustoconical wall area 150.

The simulation gives an outlet temperature T _out of 862 ° K and the temperature stratification shown in the figure, which is represented by the temperature curves 140 to 145. The temperature curve 140 corresponds to the temperature 1420 ° K, the curve 141 the temperature 1533 ° K, the curve 142 1589 ° K, the curve 143 1645 ° K, the curve 144 1702 ° K, and the curves 145 1870 ° K.

It can be seen that, despite the complex thermodynamic conditions, inter alia due to the hot wall 138 heated by the radiation from the absorber 27 and the com- plex fluidic conditions, inter alia by the convection flow generated by the temperature differences and the gravitation, there is a temperature stratification in which the temperature from the opening 3 to the outlet port 121 increases continuously, with the result that the efficiency-reducing reflection through the opening 3 is minimized can. It should also be noted that, for the specific case, the person skilled in the art can appropriately determine the direction of the inflow or the swirl or the rotation of the fluid in the absorption space about an axis running through it, as well as the location of the outlet connection (centrally according to FIGS. 2 and 3 to 6 or offset according to Figures 9 and 10). Can z. B. in the context of the other parameters (for example those of the simulation above) an optimal swirl are generated, the outlet port can also be arranged centrally with a horizontal orientation. Conversely, the combination of a comparatively weak or non-optimal swirl with an offset position of the outlet connector can produce the desired temperature stratification.

According to the knowledge of the applicant, the dimensions of the receiver 20 and all the embodiments of the absorptive receiver according to the invention can be easily scaled, the pressure having to be increased in the same ratio for a comparably high efficiency or comparable temperature ratio when the dimensions are reduced , here for example with a reduction by a factor of 10, the pressure increases by a factor of 10. However, the higher the pressure in the heat-transporting gas, the higher the efficiency tends to increase disproportionately. The conditions for a pressure of 10 bar are shown in FIG. 7c. In a specific case, the person skilled in the art can provide the excess pressure in a range between 2 and 20 bar, particularly preferably between 5 and 15 bar and very particularly preferably, as mentioned above, of 10 bar.

In the simulated embodiments according to FIGS. 3 to 10, c is in a range> 0.9, since the convection on the flat and smooth absorbing surface is very small. It should be noted that convection basically cools the absorber somewhat, and is therefore suitable for reducing the efficiency-reducing losses due to retroreflection from the opening 3, that is to say increasing the efficiency of the receiver. However, increased convection leads to increased pressure losses in the flowing gas (which in turn lowers the efficiency) and increases the construction costs of the absorber. In a specific case, the person skilled in the art can determine the optimal ratio between absorption and convection, ie a specific value for T ₃ -T ₂

(see the description of FIG. 4) in a range c> 0.3.

-T ₂

According to the applicant's knowledge, as already mentioned, a value of c = 0.3 already leads to a simpler design of the receiver according to the invention, with an efficiency which corresponds to (or is higher than) that of the known receivers designed according to the convection principle.

Since high temperatures of the absorber as well as the side walls of the absorption space are advantageous for the most intense blackbody radiation in the absorption space, coolants of all kinds are eliminated, in particular cooling channels, as is provided for receivers according to the prior art - either cooling channels in the Walls, or cooling channels in the absorber that ensure convection. The result is a receiver in which the walls of the absorption space and / or the absorber are free of coolants, in particular cooling channels. Of course, coolants for an extraordinary operating state of the receiver, such as emergency cooling systems in the event of malfunctions that by their nature do not correspond to the intended operation, are not included here. This results in a receiver in which the walls of the absorption space and / or the absorber are free of coolants for the intended operation.

In a further embodiment, not shown in the figures, the absorber is arranged in the same way as in the receiver 25 (FIG. 2) opposite the optical opening 3 and forms a wall area of the absorption space 28 (FIG. 2). In contrast to the receiver 25, however, the absorber is not seen with throughflow openings for the heat-transporting medium, but is at least partially gas-tight for this, so that heated gas on the fleas of the absorber flows radially out of the absorption space. This simplifies the construction of the absorber even further, the ratio c can be increased to a value higher than 0.3.

The person skilled in the art can, by optimizing the embodiment according to FIG. 2, or by combining this embodiment with further described features (additional section 54 of the absorber 51 according to FIG. 4, glass plate according to the embodiment not shown in the figures, etc.), the value of the ratio c Increase from> 0.3 to> 0.4 or> 0.5 or> 0.6 or> 0.7 or even to> 0.8. FIG. 13 shows the steps of a method for the operation of a preferably spatial receiver according to the present invention. In a first step 80, a suitable receiver is selected, for example with a structure according to FIG. 2, which has an absorber that can be heated by sunlight, against which gaseous, heat-transporting medium is guided by a transport device, in order to transport it through the absorber heat.

In a second step 81, a gas that absorbs in the infrared range is selected as the heat-transporting gas, in particular a heteropolar gas or one of the gases CO2, water vapor, CH4, NH3, CO, SO2, S03, FICI, NO, and NO2 (or also a Mixture of these gases) in order to absorb black body radiation from the absorber by absorption of the gas transported against the absorber even before the absorber and thus to heat the heat-transporting medium.

In a third step 82, the operating parameters of the receiver are set such that during operation of the receiver the ratio c of the temperature increase in the heat-transporting medium due to absorption in front of the absorber compared to the temperature increase due to absorption and convection at the absorber is> 0.3.

In the fourth step 83, the receiver is put into operation and moved with the parameter c> 0.3.

The result is a method for operating a receiver with a heating area for heating a heat-transporting medium, and a transport arrangement for transporting the medium through the heating area, with an opening for the radiation of the sun and a path in the heating area in the heating area Incident radiation of the sun arranged, this absorbing absorber is provided, and wherein the heat-transporting medium is a gas absorbing in frequency bands of the infrared range, which is fed to the heating region at its one end having the opening, in one with the radiation incident through the opening the common direction of the sun through this against the other end of the heating region having the absorber and is only discharged from there, and the operating parameters of the receiver are set and the gas is selected such that its temperature during transport through the heating area (to the absorber) due to absorption of radiation increases in such a way that the ratio c of the temperature increase (T ₃ - T2) due to absorption of radiation compared to the total temperature increase (T ₄ - T2) due to absorption and convection on the absorber is> 0.3.

In one embodiment, the ratio c> 0.3 is based on the absorption of only the absorber radiation, so that the temperature increases during transport through the heating region by absorption of the radiation from the absorber in such a way that the ratio c of the temperature increase (T3-T2 ) by absorption of the radiation from the absorber compared to the total temperature increase (T4 - T2) by absorption of the radiation from the absorber and convection at the absorber> 0.3.

In a specific case, the person skilled in the art can apply the ratio c> 0.3 to the absorption of only the absorber radiation 32.55 or to the absorption of the absorber radiation, including the absorption of the infrared portion of the radiation through the absorption space 28, 57 (FIGS. 2 and 4). refer to ongoing solar radiation 4.

A heteropolar gas is preferably selected as the absorbing gas, further before CO ₂ , water vapor, CH ₄ or a mixture of these gases.

The person skilled in the art can then modify the method according to the invention such that the ratio c is equal to or greater than 0.4, or 0.5 or preferably equal to or greater than 0.7, particularly preferably equal to or greater than 0.8.

In one embodiment, the method according to the invention can be designed in such a way that the gas is passed through the absorber. Alternatively, it can be provided that the gas is led past the absorber.

FIG. 14 shows the steps of a positioning method according to the invention for a receiver, for example according to FIGS. 2 to 4, wherein in step 87 the absorber is designed as a black body radiation arrangement with reduced convection and, accordingly, an absorber space cooperating with the absorber is provided in order to heat up to be able to transfer the heat-transporting gas. Then in step 88 an in frequency Bands of the infrared range absorbing gas as heat-transporting gas together with the dimensions of the absorber space are provided so that a predetermined operating state of the receiver can be defined in which the temperature increase of the heat-transporting gas by absorption (the blackbody (infrared) radiation of the absorber bers and the infrared portions of the sun compared to the temperature increase due to absorption and convection at the absorber in a ratio c> 0.3.

The result is a manufacturing method for a receiver with a heating area for heating a heat-transporting medium, and a transport arrangement for transporting the medium through the heating area, with an optical opening for sunlight and a path arranged in the path of the incident sunlight being arranged in the heating area , The sunlight-absorbing absorber is provided, characterized in that the absorber is designed as a black body radiation arrangement with reduced convection and an absorber space cooperating with the absorber is provided, as a heat-transporting medium, a gas that sorbs in frequency bands of the infrared range is provided and the Absorber space is dimensioned such that in a predetermined operating state of the receiver, the temperature of the heat-transporting medium flowing through the absorption space in an operational manner by absorption of the infrared radiation of the A bsorbers (and the infrared portion of solar radiation) increases, such that the ratio c of the temperature increase (T ₃ - T ₂ ) due to absorption in the absorber space compared to the total temperature increase (T ₄ - T ₂ ) due to absorption and convection at the absorber > 0.3.

A heteropolar gas is preferably provided as the gas, particularly preferably CO ₂ , water vapor, CH ₄ , NH ₃ , CO, SO ₂ , SO ₃ , HCl, NO, and NO ₂ or a mixture of these gases.

In one embodiment of the invention, the ratio c is set equal to or greater than 0.4, preferably 0.5, particularly preferably 0.6, very preferably 0.7 and most preferably 0.8.

Finally, in a further embodiment, a secondary absorber designed as a blackbody radiation arrangement with reduced convection can be provided in the absorber space, and the receiver can furthermore preferably be designed as a spatial receiver.

Claims

1. A method for operating a receiver (25, 50, 100, 120) with a heating area (26) for heating a heat-transporting medium, and a trans port arrangement (29) for transporting the medium through the heating area (26), wherein in the heating area (26) an opening (3) for the radiation (4) of the sun and an arranged in the path of the incident radiation (4) of the sun, which is provided from sorbing absorber (27), characterized in that an in Frequency bands of the infrared region absorbing gas is provided, which is supplied to the heating region (26) in the flow direction behind the opening (3), and in this in one of the directions with the incident through the opening (3) and directly onto the absorber (27, 51) falling solar radiation (4) common transport direction from its one, the opening (3) having end against its other, the opening (3) opposite and de n Absorbers (27, 51) have the end, guided and only there from the heating area (26), and that the operating parameters of the receiver (25, 50, 100, 120) are set and the gas is selected such that its temperature during transport by the heating area (26) by absorption of radiation (4) increases such that the ratio c of the temperature increase (T ₃ - T ₂ ) by absorption of radiation (4) compared to the total temperature increase (T4 - T ₂ ) by the Absorption and convection at the absorber ber (27.51)> 0.3.

2. The method according to claim 1, wherein the temperature increases during the transport through the heating region (26) by absorption of the radiation from the absorber (27) such that the ratio c of the temperature increase (T ₃ - T ₂ ) by absorption of the radiation from the Absorber (27) compared to the total temperature increase (T ₄ - T ₂ ) due to the absorption of the radiation from the absorber and convection at the absorber (27.51)> 0.3.

3. The method according to claim 1, wherein the heating region is arranged in the path of the incident radiation (4) of the sun, between the opening (3) and the absorber (27,51) provided absorber space (28), and wherein the ratio c is the ratio of the temperature increase (T3 - T2) by absorption of the radiation from the absorber (27) in this absorber space to the total temperature increase (T4 - T2 ) by absorption and convection at the absorber (27) after the gas has passed through it.

4. The method according to claim 1, wherein the heating region (26) has two absorber spaces (28) with a common absorber (27, 51), and wherein the ratio c is provided for one or both of the absorber spaces.

5. The method of claim 1, wherein the gas is a heteropolar gas, preferably one or a mixture of the gases CO2, water vapor, CH4, N H3, CO, SO2, SO3, HCl, NO, and NO2, be particularly preferably a mixture with Water vapor and CO2.

6. The method according to claim 1, wherein the ratio c is equal to or greater than 0.5 or preferably equal to or greater than 0.7, particularly preferably equal to or greater than 0.8.

7. The method according to claim 1, wherein gas is passed through the absorber (27, 51).

8. The method according to claim 1, wherein gas is guided past the absorber (27, 51).

9. The method according to claim 1, wherein the gas in the heating region (26) is pressurized, preferably in a range between 2 and 20 bar, particularly preferably between 5 and 15 bar, very particularly preferably 10 bar.

10. The method of claim 1, wherein gas is passed around the absorber (27, 51) to a rear of the absorber (27, 51) and then away from it.

11. The method according to claim 1, wherein the gas which is heated by absorption of the radiation from the absorber (27m51) is removed from an absorber chamber (28, 53) as soon as it is partially heated and / or a partially heated gas is supplied to an absorber chamber (28, 53) is, and wherein the supply takes place in the absorber space (28,53) at the respective location, where the temperature in the absorber space (28,53) essentially corresponds to the temperature of the partially warmed gas.

12. The method according to claim 1, wherein the infrared absorbing gas is supplied to the heating region (26) tangentially to the transport direction, such that in the transport region in the transport direction against the absorber (27, 51) gas is additionally guided around an axis parallel to the transport direction ( 127) rotates.

13. The method according to claim 1, wherein the infrared absorbing gas in an absorption space (28, 53) of the heating region (26) is set in rotation such that it has a swirl in the absorption space about an axis parallel to the transport direction (127) points.

14. Receiver (25, 50, 100, 120) for carrying out the method according to claim 1 or produced by the method according to claim 29, with a heating region (26) for the heating of a heat-transporting medium, which has an opening (3) for the radiation (4) the sun, and having an absorber (27, 51) arranged in the path of the incident radiation (4) of the sun, with a transport arrangement (29) for transporting the medium through the heating region (26), characterized in that an absorber space (28, 57) is also provided for heating the heat-transporting medium, one end of which passes through the opening

(3) for the radiation of the sun and the other end thereof is formed by the absorber (27, 51) lying opposite the opening (3), in such a way that radiation (4) entering the sun directly and through the opening (3) essentially falls completely on the absorber (27, 51), and the absorber (27, 51) is designed as a radiation arrangement acting in the absorber space (28, 57) and the transport arrangement (29) for the transport of a gas as a heat-transporting medium , and this in the region of the opening (3), but in the direction of the incident radiation (4) behind the opening (3) for the radiation

(4) feeds the sun to the absorber chamber (28,57) and removes it from the absorber chamber (28,57) in the area of the absorber (27,51), such that the heat-transporting medium transports the absorber chamber (28,57 ) in an incident direction corresponding to solar radiation (4) from one end with the opening (3) to the other end with the absorber (27, 51), and wherein the heat-transporting medium is essentially a gas that absorbs in frequency bands of the infrared range , and the absorber space (28, 57) interacting with the absorber (27, 51) is dimensioned such that during operation the ratio c of the temperature increase (T ₃ - T ₂ ) of the in Frequency bands of the infrared range absorbing, heat transporting Ga ses by absorption in the absorber space (28.57) compared to the temperature increase (T4 - T2) by absorption and convection at the absorber (27.51),> 0.3.

15. Receiver (25, 50, 100, 120) according to claim 14, wherein the absorber space (28, 57) is measured in such a way that, in operation, the ratio c of the temperature increase (T ₃ - T ₂ ) of the heat-absorbing in frequency bands of the infrared range absorbs Gas by absorption of the radiation from the absorber (27.51) in the absorber chamber (28.57) compared to the temperature increase (T4 - T ₂ ) by absorption of the radiation from the absorber (27.51) and convection at the absorber (27.51 ),> 0.3.

16. Receiver (25, 50, 100, 120) according to claim 14, wherein an absorber space (28, 57) is arranged between the opening (3) for the radiation (4) from the sun and the absorber (27, 51), and wherein c is the ratio is from the temperature increase (T3 - T ₂ ) by absorption of the radiation of the absorber in this absorber space (28,57) to the total temperature increase (T4 - T ₂ ) by absorption and convection at the absorber (27,51), according to the gas has passed this

17 receiver (25, 50, 100, 120) according to claim 14, wherein the heating region has two absorber spaces (28, 57) which the absorber (27, 51) has in common and wherein the ratio c for one or both of the absorber spaces (28, 57 ) is provided, preferably around the absorber (27, 51) leading connecting channels connecting the two absorber spaces (28, 57) together.

18. Receiver (25, 50, 100, 120) according to claim 14, wherein the absorber (27, 51) at least partially has a gas-tight surface (27 ') and is preferably plate-shaped.

19. Receiver (25, 50, 100, 120) according to claim 14, wherein the walls of the absorption space (28, 57) and / or the absorbers (27, 51) are free of coolants, in particular cooling channels.

20. Receiver (25, 50, 100, 120) according to claim 14, wherein the walls of the absorption space (28, 57) and / or the absorbers (27, 51) are free of coolants, in particular cooling channels, for the intended operation of the receiver (25, 50,100,120).

21. Receiver (25, 50, 100, 120) according to claim 14, wherein in operation the heat-transporting gas contains a heteropolar gas, preferably one or more of the gases C0 ₂ , water vapor, CH4, NH ₃ , CO, S0 ₂ , S03, HCl, NO, and N0 ₂ , and particularly preferably a mixture with steam and C0 ₂ .

22. Receiver (25, 50, 100, 120) according to claim 14, wherein a secondary absorber (54) is provided in an absorption space (28, 57) and is arranged and designed such that it can be heated by the infrared radiation of the absorber (27, 51) and in Operation via its radiation in turn acts in the absorber space (28, 57), it preferably being plate-shaped and particularly preferably essentially not shading the absorber.

23. Receiver (25, 50, 100, 120) according to claim 14, wherein the transport arrangement has one or more lines (91 to 91 "', 92 to 92"') connected to an absorber space (28, 57) for heat-transporting gas, which are arranged in this way are that partially heated gas can be removed from the absorber chamber (28, 57) and / or partially heated gas can be supplied at a location at which the temperature of the gas in the absorber chamber (28, 57) essentially corresponds to the temperature of the partially heated, supplied gas.

24. Receiver (25, 50, 100, 120) according to claim 14, wherein an absorber space (28, 57) is designed for a pressure of the gas in a range between 2 and 20 bar, particularly preferably between 5 and 15 bar, very particularly preferably 10 bar.

25. Receiver (25, 50, 100, 120) according to claim 14, wherein the ratio ^ is equal to or greater than 0.5 or preferably equal to or greater than 0.7, particularly preferably equal to or greater than 0.8.

26. Receiver (25, 50, 100, 120) according to claim 14, wherein the transport arrangement (29) is designed such that, during operation, the heat-transporting medium at least during the crossing of the absorber space (28, 57) in the transport direction partially has a twist around an axis (127) of the absorber chamber (28, 57) parallel to the transport direction, the transport arrangement (29) preferably having inlet openings for the medium provided on the absorber chamber (28, 57), which are opposite the axis (103 ) of the absorber chamber (28, 57) are oriented tangentially in the same swirl direction.

27. Receiver (25, 50, 100, 120) according to claim 14, wherein the transport arrangement in the absorber space (28, 57) has openings for the heat-transporting medium which are arranged adjacent to a wall 138 of the absorption space (28, 57) and which In the main flow direction, a flow component of the fluid flowing into the spray chamber (28, 57) is generated with an inclination to the wall 138 of less than 15 degrees, preferably equal to or less than 10 degrees, particularly preferably equal to or less than 5 degrees.

28. Receiver (25, 50, 100, 120) according to claim 14, wherein the transport arrangement in the absorber space (28, 57) has openings for the heat-transporting medium, which are tangential to an axis 127 of the absorption space (28, 57) fluid flowing into the absorption space (28, 57).

29. Manufacturing method for a receiver (25, 50, 100, 120) with a heating area for heating a heat-transporting medium, and a transport arrangement (29) for transporting the medium through the heating area, an optical opening (3) for Sunlight and an arranged in the path of the incident sunlight, the sunlight absorbing absorber (27, 51) is provided, characterized in that the absorber (27, 51) is designed as a radiation arrangement and an absorber space interacting with the absorber (27, 51) (28,57) is provided, in which the opening (3) and the absorber (4) lie opposite each other and delimit the absorber space (28,57), and as a heat-transporting medium a gas absorbing in frequency bands of the infrared range in the direction of the sunlight falling through the opening directly onto the absorber (27, 51) is guided to the absorber (27, 51) and is read in this way hen and the absorber space (28, 57) is dimensioned such that, in a predetermined operating state of the receiver, the temperature of the heat-transporting medium flowing operationally through the absorption space (28, 57) by absorption of the infrared radiation of the absorber also increases, such that the ratio c of the temperature increase (T3 - T2) due to absorption in the absorber space (28.57) compared to the total temperature increase (T4 - T2) due to absorption and convection at the absorber (27.51)> 0, 3 is.

30. The method of claim 29, wherein an absorber space (28,57) in the path of the incident

Sun radiation between the opening and the absorber (27.51) is arranged, and the ratio c as the ratio of the temperature increase (T ₃ - T ₂ ) by absorption of the radiation of the absorber (27.51) in this absorber space (28.57 ) to the total temperature increase (T ₄ - T ₂ ) by absorption and convection at this absorber, after which the gas has passed through it.

31. The method according to claim 29, wherein the gas comprises a heteropolar gas, preferably one or more of the gases C0 ₂ , steam, CH ₄ , NH ₃ , CO, SO ₂ , SO ₃ , HCl, NO, and NO ₂ and particularly preferably a mixture with water vapor and CO ₂ ..

32. The method according to claim 29, wherein the ratio c is equal to or greater than 0.4, preferably 0.5, particularly preferably 0.6, very preferably 0.7 and most preferably 0.8.

33. The method according to claim 29, wherein a secondary absorber (54) designed as a radiation arrangement is provided in the absorber space (28, 57).