Absorber device and method for operating an absorber device

Abstract

The invention relates to an absorber device (100) in which solid particles (180) are heated by concentrated solar radiation, and to a method for operating such an absorber device (100). The absorber device (100) comprises an inclined plane (130) which is provided for transporting the solid particles (180) and which has at least one metering region (132) and a plurality of steps (134). The steps (134) each have a support surface (136), which are each spaced apart in the vertical direction (z) by a distance (137). An angle of inclination (β) of the support surfaces (136) of the steps (134) relative to a horizontal plane (HE) is selected such that a first portion of the solid particles (182) remains on the support surfaces (136) of the steps (134), and the first portion of the solid particles (182) forms a particle bed. A second portion of the solid particles (184) moves over the particle bed.

Description

[0001] Absorber device and method for operating an absorber device

[0002] The invention relates to an absorber device and a method for operating an absorber device.

[0003] State of the art

[0004] Solid particles, such as granular ceramic media, are well-known as heat transfer and storage media, for example in concentrating solar tower power plants. These solid particles offer many advantages. For instance, they enable heating to very high temperatures using concentrated solar energy. Furthermore, solid particles can be an essential component of many thermochemical processes developed as alternatives to fossil-fueled methods. These include, for example, redox cycles for synthesis gas production, high-temperature processes in cement manufacturing, and scrap metal recycling.

[0005] Heating solid particles using concentrated solar energy to target temperatures of up to 1000°C is also known.

[0006] Furthermore, absorber devices and methods for operating such absorber devices are known. For example, DE 102016216733 B4 describes a solar radiation receiver for the solar irradiation of solid particles, with an absorber device in which the solid particles are heated by concentrated solar radiation. The absorber device comprises a horizontal conveying device with a horizontally arranged conveying surface. The conveying surface is movable in at least one main conveying direction, and the solid particles can be transported on the conveying surface. The concentrated solar radiation is directed onto the conveying surface.

[0007] Disclosure of the invention

[0008] The object of the invention is to provide an improved absorber device.

[0009] DLR-4347WO

[0010] 2025-12-22 Another object of the invention is to provide a method for operating an improved absorber device.

[0011] The problems are solved by the features of the independent claims. Favorable embodiments and advantages of the invention become apparent from the further claims, the description, and the drawings.

[0012] According to one aspect of the invention, an absorber device is proposed in which solid particles are heated by concentrated solar radiation. The device comprises an inclined plane for transporting the solid particles and has at least one metering area and several stages. Each stage has a support surface spaced apart vertically. The solid particles strike the inclined plane at the at least one metering area and move from there to a particle discharge area. The movement of the solid particles can depend, among other things, on the inclination of the inclined plane, the slope of which depends on the angle of inclination of the inclined plane to a horizontal plane. The concentrated solar radiation is directed onto at least one region of the inclined plane and heats the solid particles in that region.The angle of inclination of the step's bearing surfaces relative to the horizontal plane can be chosen such that a first proportion of the solid particles remains on the bearing surfaces of the respective steps, forming a particle bed. A second proportion of the solid particles moves across this particle bed.

[0013] The absorber device according to the invention advantageously enables the heating of the solid particles by having the solid particles move through an irradiation zone in which solar radiation strikes the inclined plane. The speed and thus the residence time of the solid particles in the irradiation zone can be advantageously adjusted by the angle of inclination of the inclined plane, so that the solid particles can be heated to the desired temperature.

[0014] DLR-4347WO

[0015] 2025-12-22 Additionally or alternatively, the inclined plane can be moved, for example, in a horizontal direction, so that the solid particles can be moved by a horizontal movement of the inclined plane. This allows the residence time of the solid particles in the irradiation area to be advantageously adjusted so that the solid particles can be heated to the desired temperature. Here, the movement of the inclined plane in a horizontal direction, particularly in the longitudinal direction, can be used as the primary means of adjusting the velocity and residence time of the solid particles.

[0016] Relevant parameters of the absorber device according to the invention are the residence time of the solid particles on the inclined plane, particularly in the irradiation zone of the inclined plane, the mass flow rate of the solid particles, and the layer thickness of the solid particles on the inclined plane. These parameters influence each other and affect the heating of the solid particles. For example, an increase in the residence time of the solid particles with a constant mass flow rate leads to a greater layer thickness of the solid particles. The increased residence time allows the solid particles to be exposed to solar radiation for a longer period, while the increased layer thickness can result in uneven heating of the solid particles within the layer, with solid particles facing the solar radiation heating up more quickly.are heated as underlying solid particles.

[0017] Factors influencing the residence time of the solid particles include, among others, an acceleration profile of the inclined plane and / or a relative position of the inclined plane, in particular of the at least one dosing area to an inlet and / or the inclination of the inclined plane and / or the inclination of the support surfaces.

[0018] Advantageously, as the solid particles move down the steps of the inclined plane, they are heated to high temperatures, particularly above 1000°C, by concentrated solar radiation. The steps ensure that the solid particles remain on the inclined plane and that the conveyed solid particles move over the solid particles remaining on the steps.

[0019] DLR-4347WO

[0020] 2025-12-22 Advantageously, the particle bed formed by the remaining solid particles constituting the first fraction can protect the material of the inclined plane and the steps from excessively high temperatures and / or excessively large temperature gradients and thus from thermomechanical stresses.

[0021] Advantageously, the first fraction of solid particles, and thus the layer thickness of the particle bed, can be influenced or even controlled by selecting the shape and number of steps. Since the particle bed, together with the layer created by the moving second fraction of solid particles, forms a layer thickness of solid particles on the inclined plane, the layer thickness of the solid particles on the inclined plane can also be at least partially influenced or controlled by the shape and number of steps. Thin layer thicknesses of the moving layer, 2-4 particle diameters, are advantageous in this context to enable high heat transfer to the solid particles.

[0022] Advantageously, the number and shape of the steps can ensure that the lowest layer of particles, which forms the particle bed, hardly moves or does not move at all relative to the inclined plane. This results in a particle layer that remains on the inclined plane for a very long time, allowing other particle layers to move more quickly over it. For example, unlike an inclined plane without steps, the steps on an inclined plane with steps can make avalanche-like sliding processes more difficult or completely impossible, thus increasing the residence time of the solid particles in the first layer, which forms the particle bed and constitutes the lower layer of solid particles on the inclined plane.Advantageously, the second fraction of solid particles, which moves across the particle bed, can be exposed to the highest solar radiation as the uppermost particle layer and simultaneously have the shortest residence time on the inclined plane. The first fraction of solid particles, which forms the particle bed and is located below, is exposed to low solar radiation but has a longer residence time on the inclined plane and therefore has more time to heat up.

[0023] DLR-4347WO

[0024] December 22, 2025: The longer the residence time of the solid particles on the inclined plane, the longer the concentrated solar radiation can act upon them. The longer the concentrated solar radiation can act upon the solid particles, the higher the temperatures to which the solid particles can be heated. For example, a residence time of two to three seconds is required to heat a solid particle.

[0025] Advantageously, the moving solid particles exhibit a relatively uniform velocity at the surface of the inclined plane. The lower layers of the solid particles remain, as desired, on the inclined plane.

[0026] The absorber device according to the invention can, for example, be arranged in a solar thermal power plant or in a reactor, or can be an element of such a reactor in which a solar radiation receiver with such an absorber device is arranged on or in a tower, wherein solar radiation is reflected onto the solar radiation receiver by means of numerous heliostats of a heliostat field surrounding the tower. A high radiation concentration thus arises at the solar radiation receiver, which allows suitable solid particles to be heated to high temperatures.

[0027] When irradiated with concentrated solar radiation, the solid particles absorb at least some of the concentrated solar radiation, thereby heating the solid particles. These particles can then either be used as a heat transfer medium, allowing the thermal energy to be transported to a consumer via the solid particles, or the high temperature triggers a chemical reaction within the solid particles. This reaction can take place either in the absorber device, in a collection chamber connected to the absorber device, and / or in a reactor of the solar radiation receiver.

[0028] DLR-4347WO

[0029] 2025-12-22 According to a favorable design of the absorber device, the inclined plane can be movable in the horizontal direction. For example, a drive element, particularly via a coupling, can move the inclined plane in the horizontal direction. In the following, the horizontal direction is understood to be a direction perpendicular to the direction of gravity, which contributes to the inclination direction of the inclined plane, for example, a longitudinal direction. In the following, the inclination direction is understood to be the direction of movement of the solid particles on the inclined plane.

[0030] By moving the inclined plane, particularly by accelerating it in the horizontal direction (which contributes to the inclination direction, with the horizontal direction being the longitudinal direction), the solid particles on the steps can be accelerated and / or moved, thereby conveying them down the steps. This advantageously allows for the adjustment of the mass flow rate and particle flow behavior. For example, the mass flow rate and particle flow behavior can be kept constant in the absorber device despite changing temperatures, thus enabling stable operation. In this case, adjusting the inclination angle is unnecessary; adjusting the movement of the inclined plane in the horizontal direction, which can be an oscillatory motion, is sufficient to compensate for changes in particle flow behavior due to temperature variations.

[0031] Additionally or alternatively, the inclination or angle of the inclined plane can be used to adjust the acceleration required for the movement of the solid particles, thereby maintaining, for example, a constant mass flow rate and particle flow behavior in the absorber device despite changing temperatures. A combination of changing the angle of inclination and the inclination of the plane is also possible.

[0032] Additionally or alternatively, a horizontal distance between a rotary axis and an inlet can be adjustable. For example, a drive element, particularly via a coupling, can move the inclined plane in a horizontal direction.

[0033] DLR-4347WO

[0034] 2025-12-22 For example, the starting position of an oscillatory motion of the inclined plane can be determined by this horizontal distance between the axis of rotation and the inlet. Furthermore, the position of a pile cone on the inclined plane, which forms below the inlet, can be determined by the horizontal distance between an axis of rotation and an inlet. The smaller the horizontal distance between the axis of rotation and the inlet, the further the corresponding pile cone is located from the first stage. The greater the distance between the inlet and the axis of rotation, the closer the corresponding pile cone is to one of the stages of the inclined plane. The mass flow rate of the solid particles can also be adjusted by the distance of the pile cone to the stages.

[0035] The motion of the inclined plane can be an oscillatory motion with an amplitude and a period. For example, the inclined plane can be accelerated in the horizontal direction, particularly in the longitudinal direction, and then decelerated. A zero point, defined as the horizontal distance between the axis of rotation and the inlet, can be specified in the horizontal direction, around which the inclined plane oscillates to accelerate the solid particles. Advantageously, significantly lower accelerations are required to move the solid particles in the inclined plane compared to a horizontally arranged plane. The period and / or the amplitude of the motion can be used to control the mass flow rate. Additionally or alternatively, the period and amplitude of the motion can be used to control the residence time of the solid particles.The movement of the inclined plane advantageously eliminates the need for a metering mechanism, such as one for adjusting the layer thickness of the solid particles on the inclined plane. This is particularly beneficial at very high temperatures. For example, metering mechanisms may have orifices that can become clogged at high temperatures, especially if impurities in the solid particles or if small particles or dusts are deposited on the orifices and sinter into solid at high temperatures. By eliminating such a metering mechanism, the solid particles can enter the metering area through an inlet, and clogging of this inlet is more easily prevented due to the absence of an orifice.

[0036] DLR-4347WO

[0037] 2025-12-22 According to a favorable embodiment of the absorber device, the driving motion of the inclined plane in the horizontal direction, particularly in the longitudinal direction, can be a periodic motion, especially a sinusoidal motion. The mass flow rate and / or the residence time of the solid particles can be adjusted by the duration of the period. The longer the duration of the period, the greater the residence time of the solid particles and the lower the mass flow rate of the solid particles. The period should not be too short to avoid excessively high accelerations, which in turn can lead to high mechanical stress on the inclined plane. For example, an acceleration of the inclined plane of a maximum of 10% of the acceleration due to gravity can be used.

[0038] In a favorable design of the absorber device, at least one adjustment element can be provided to set the inclination angle of the inclined plane. For example, a drive can actuate this adjustment element depending on the temperature of the solid particles. By setting the inclination angle of the inclined plane just before the point at which the particles would slide off on their own, the horizontal acceleration required to transport the solid particles can be kept low. The inclination angle of the inclined plane depends on the particle properties, such as their size, shape, coefficient of friction, and / or density. For example, an inclination angle between 25° and 30° to the horizontal plane is conceivable for certain solid particles. For other solid particles, an inclination angle between 24° and 28° to the horizontal plane is conceivable.For additional solid particles, an inclination angle between 26° and 32° to the horizontal plane is conceivable. Additionally or alternatively, the mass flow rate of the solid particles can be adjusted using the first adjustment element.

[0039] The coefficients of friction between the solid particles and between the walls and the solid particles change with temperature. This alters the flow behavior of the solid particles during the heating process of the absorber device. To compensate for this, the inclination angle of the inclined plane can be advantageously adjusted.

[0040] DLR-4347WO

[0041] 2025-12-22 For example, in a certain type of solid particle, the friction between the particles can increase with temperature, and experiments have shown that this reduces the flow velocity at a constant inclination of the inclined plane. In such a case, the angle of the inclined plane can be increased to compensate for the increased friction. An increase in the inclination angle of approximately 2° may be sufficient. The adjustment of the inclination angle can vary depending on the properties of the solid particles, so that an inclination angle adjustment can be specified for each particle type.

[0042] The adjusting element can, for example, be designed as a toggle lever mechanism. The toggle lever mechanism can be driven, for example, by a stepper motor. With the underlying toggle lever principle, the transmission ratio between applied force and resulting force can continuously change during movement.

[0043] In its bent position, the toggle lever provides a high stroke rate with a low force transmission. As the toggle mechanism approaches its extended position, the stroke rate decreases at a constant actuation speed, while the pressing force increases. The incline of the inclined plane can be finely adjusted by the adjustment element, which is driven by the stepper motor and also functions as a toggle lever mechanism. This toggle lever mechanism can essentially be operated in its extended position, allowing for very precise adjustment of the plane's incline with minimal force and a high reduction ratio.

[0044] Advantageously, a slight adjustment of the inclination by a few degrees, for example by 2°, can be implemented during the heating process of the absorber device to compensate for the changing coefficient of friction of the solid particles with temperature. This advantageously allows the mass flow and particle flow behavior to be kept constant in the absorber device despite changing temperatures, thus enabling stable operation.

[0045] DLR-4347WO

[0046] 2025-12-22By changing the inclination of the plane, the horizontal accelerations for transporting the solid particles can be significantly reduced or increased as needed.

[0047] Furthermore, by adjusting the tilt angle, the residence time of the solid particles in the area where the concentrated solar radiation hits the inclined plane can be advantageously adjusted or predetermined.

[0048] According to a favorable embodiment of the absorber device, a distance between at least one inlet and the at least one dosing area can be adjusted. For example, a second adjustment element can be provided which sets a distance between at least one inlet and the at least one dosing area.

[0049] For example, the adjusting element can change the position of at least one inlet in the vertical direction, which runs parallel to the direction of gravity, in order to change the distance to the corresponding dosing area.

[0050] Additionally or alternatively, the inclined plane can also be moved upwards to move the at least one dosing area upwards and to vary the distance to the at least one inlet. Advantageously, by varying the distance between the at least one inlet and the at least one corresponding dosing area, the residence time and / or the mass flow rate of the solid particles on the inclined plane can be influenced. For example, the mass flow rate is higher at a greater distance than at a smaller distance.

[0051] In a favorable embodiment of the absorber device, at least one distributor is arranged above the at least one metering area, distributing the solid particles to the at least one metering area. The distributor can, for example, form the at least one inlet. The solid particles can be fed to the distributor via a particle feed opening, which can, for example, be designed as a pipe. The distributor can have several distributor outlets forming the inlets.

[0052] DLR-4347WO

[0053] 2025-12-22 Each inlet can be assigned to a dosing area. For example, the dosing areas can be arranged transversely to the inclined plane. The second adjustment element can vary the position of the distributor and / or the positions of the respective distributor outlets forming the inlets in order to increase or decrease the distance to the corresponding dosing areas.

[0054] The solid particles can fall from the distributor onto the inclined plane. For this purpose, an orifice can be provided, for example, to regulate the particle flow. The layer thickness of the solid particles on the inclined plane can be advantageously regulated via the distributor, depending on the incline and the temperature of the solid particles. This ensures that a relatively uniform layer thickness of solid particles is applied to the inclined plane.

[0055] In a favorable embodiment of the absorber device, the steps can be formed from strips arranged transversely to the direction of inclination. The strips can be made of aluminum oxide. The strips can be narrow in the direction of inclination or flow of the solid particles, or along the longitudinal direction, and therefore, under thermal stress, expand primarily in the direction transverse to the flow of the solid particles or transverse to the horizontal direction, particularly transverse to the longitudinal direction. This can advantageously reduce thermomechanical stresses. The steps can be formed from commercially available, dense aluminum oxide ceramic strips. Aluminum oxide ceramic strips are characterized by high heat resistance and are also very durable, thus making abrasion of the steps difficult or even impossible.The ceramics can be produced by pressing AhOa powder into a mold to create a green body. This is then sintered at very high temperatures, allowing for the creation of a specific texture, surface structure, and / or roughness of the steps. For example, surface structures with jagged edges of approximately two millimeters are conceivable.

[0056] DLR-4347WO

[0057] 2025-12-22 According to a favorable embodiment of the absorber device, a holding arrangement with at least two components can hold the strips in a form-fit and / or force-fit manner. The at least two components can, in particular, be designed as porous vacuum-formed parts made of aluminum silicate with a high aluminum oxide content. Due to the strip geometry, thermal expansion occurs almost exclusively in one dimension, which can advantageously reduce thermomechanical stresses. The porous vacuum-formed parts are advantageously heat-resistant. In particular, the holding arrangement can allow the strips forming the steps to be displaced in a direction orthogonal to the direction of movement of the solid particles, so that the elongation of the steps can be compensated for. At the same time, the steps are fixed in the horizontal direction, especially in the longitudinal direction of the absorber device, or have little play in the holding device.

[0058] With a favorable design of the absorber device, the angle of inclination between the support surfaces and the horizontal plane can range from -5° to +10°. This angle influences the mass flow rate and the residence time of the solid particles. Furthermore, the support surface can impede further slippage of the solid particles or reduce their velocity. If the angle of inclination of the support surfaces of the steps to the horizontal plane is zero, the step cuts into the inclined plane perpendicular to the direction of gravity. If the angle of inclination of the support surfaces of the steps to the horizontal plane is less than 0°, the step cuts into the inclined plane in such a way that the orientation of the support surface is opposite to the orientation of the inclined plane. This reduces the probability of solid particles moving further on the support surface.The greater the positive angle of inclination of the steps to the horizontal plane, the more the shape of the contact surface resembles the shape of the inclined plane, and the fewer solid particles remain on the contact surface. This results in a shorter residence time and a higher mass flow rate.

[0059] DLR-4347WO

[0060] 2025-12-22 According to a favorable embodiment of the absorber device, the inclined plane can be arranged in a closed housing, which has at least one radiation inlet opening for concentrated solar radiation and the particle removal area. Furthermore, the housing can have a particle feed for the at least one distributor. The hot solid particles can be collected and removed in the particle removal area. The closed housing prevents radiation losses, since the concentrated solar radiation entering the housing through the radiation inlet opening remains largely within the housing and warms the cavity enclosed by the housing. The housing can thus serve as a radiation trap.

[0061] In a favorable design of the absorber device, a radiation blocker can be arranged below the inclined plane. The radiation blocker can have labyrinthine structures. The radiation blocker can allow movement of the inclined plane and simultaneously at least reduce heat loss in the cavity within the housing.

[0062] The radiation blocking barrier prevents a direct optical path between hot inner surfaces of the housing cavity and colder surfaces and / or the colder environment outside the cavity. The radiation blocking barrier can be created by two interlocking lamellar structures, resulting in a meandering path for the radiation. Small gaps between the lamellar structures minimize radiation losses. The radiation blocking barrier can advantageously reduce radiation losses and, consequently, heat losses. Furthermore, the radiation blocking barrier can close gaps that may occur when adjusting the inclination of the inclined plane.

[0063] According to a further aspect of the invention, a method for operating an absorber device according to the invention is described. The method comprises the following steps: Transferring the solid particles onto at least one metering area on an inclined plane, which is provided for transporting the solid particles and has several stages, each of which has a support surface, which are spaced apart in the vertical direction. DLR-4347WO

[0064] 2025-12-22 Irradiation of the inclined plane and the solid particles located thereon with concentrated solar radiation, wherein the solid particles are moved from at least one metering area to a particle removal area, wherein an inclination of the support surfaces of the steps relative to the inclined plane is chosen such that a first proportion of the solid particles remains on the support surfaces of the respective steps and forms a particle bed, wherein a second proportion of the solid particles moves over the particle bed.

[0065] The advantages of the absorber device according to the invention also apply to the method according to the invention and are not repeated here.

[0066] The method according to the invention advantageously enables very homogeneous heating of the solid particles by means of concentrated solar radiation. By transporting the solid particles on the inclined plane with steps, the residence time of the solid particles in a region irradiated with the concentrated solar radiation can be advantageously adjusted so that the desired temperature is reached.

[0067] drawing

[0068] Further advantages become apparent from the following description of the drawings. The figures illustrate exemplary embodiments of the invention. The figures, the description, and the claims contain numerous features in combination.

[0069] The expert will expediently consider the features individually and combine them into meaningful further combinations.

[0070] They show, for example:

[0071] Fig. 1 shows a schematic representation of an absorber device according to an embodiment of the invention;

[0072] Fig. 2 shows a schematic representation of a holding arrangement for the steps of the inclined plane of the absorber device from Figure 1;

[0073] DLR-4347WO

[0074] 2025-12-22Fig. 3 a schematic sectional view of the inclined plane of the absorber device from Figure 1;

[0075] Fig. 4 shows a schematic detail of the sectional view of the inclined plane of the absorber device from Figure 3;

[0076] Fig. 5 is a schematic representation of a step geometry of the steps of the inclined plane according to Figure 1;

[0077] Fig. 6 shows a graphical representation of the effect of the period of motion of the inclined plane on the mass flow, residence time and maximum acceleration of the inclined plane;

[0078] Fig. 7 is a graphical representation of the effect of the inclination angle α of the inclined plane to the horizontal plane according to Figures 1 to 5 on the mass flow rate and on the residence time;

[0079] Fig. 8 is a graphic representation of the effect of the inclination angle β of the step geometry according to Fig. 5 on the mass flow rate and residence time;

[0080] Fig. 9 shows a schematic representation of a radiation blockage for an absorber device according to Figure 1 at a first inclination angle a and

[0081] Fig. 10 shows a schematic representation of a radiation blockage for an absorber device according to Figure 1 at a second tilt angle a.

[0082] Embodiments of the invention

[0083] In the figures, similar or equivalent components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0084] DLR-4347WO

[0085] 2025-12-22 Before the invention is described in detail, it should be noted that it is not limited to the respective components of the device, as these components may vary. The terms used here are intended solely to describe particular embodiments and are not used restrictively. Furthermore, where the singular or indefinite articles are used in the description or in the claims, this also refers to the plural of these elements, unless the overall context clearly indicates otherwise.

[0086] The directional terminology used below, including terms like "left," "right," "above," "below," "in front," "behind," "after," and the like, serves only to improve the understanding of the figures and is in no way intended to limit their generality. The components and elements depicted, their interpretation, and their use may vary according to the considerations of a person skilled in the art and be adapted to the specific applications.

[0087] As can be seen from Figure 1, an absorber device 100 according to the invention comprises an inclined plane 130, shown in Figures 1 to 3, which is provided for transporting solid particles 180. The inclined plane 130 has at least one metering area 132 and several steps 134. On an upper region of the inclined plane 130, several metering areas 132 can be arranged side by side in the transverse direction y of the inclined plane 130, or a continuous metering area 132 extending in the transverse direction y can be arranged.

[0088] The inclined plane 130 is inclined to a horizontal plane HE. The horizontal plane HE is perpendicular to the vertical direction z, which runs in the direction of gravity. Furthermore, the horizontal plane HE is spanned by the transverse direction y and the longitudinal direction x. The angle of inclination α, which defines the slope of the inclined plane 130, is shown between the inclined plane 130 and the horizontal plane HE.

[0089] As can be seen from Figures 3 to 5, the steps 134 of the inclined plane 130 of the absorber device 100 according to the invention each have a support surface 136, which are each spaced apart by a distance 137 in the vertical direction z.

[0090] DLR-4347WO

[0091] 2025-12-22 The support surfaces 136 each cut into the inclined plane 130. The distance 137 between the support surfaces 136 can be formed by a rear stop. This stop limits the respective step 134.

[0092] As can be seen from Figures 1 to 4, the solid particles 180 strike the inclined plane 130 at the at least one metering area 132 and form a cone of material in this area. The solid particles 180 move from the at least one metering area 132 to a particle discharge area 160, shown in Figure 1. The inclination of the inclined plane 130 can contribute to the movement of the solid particles 180.

[0093] The solid particles 180 can be formed as granular, ceramic media.

[0094] As can be further seen from Figure 1, in the illustrated embodiment, the area of ​​the inclined plane 130 on which the concentrated solar radiation is directed corresponds to the area of ​​the entire inclined plane 130. The concentrated solar radiation warms or heats the solid particles 180 in this area.

[0095] In an alternative embodiment, the area on which the concentrated solar radiation is directed can also be smaller. Furthermore, several areas instead of one continuous area are also conceivable.

[0096] As can be seen from Figure 1, in the illustrated embodiment the radiation inlet opening 192 is arranged in the longitudinal direction x opposite the inclined plane 130 and the concentrated solar radiation falls from the longitudinal direction x onto the inclined plane 130.

[0097] In an alternative embodiment not shown, the radiation inlet opening 192 can also be arranged in the vertical direction z above the inclined plane 130, so that the concentrated solar radiation falls from the vertical direction z onto the inclined plane 130. The concentrated solar radiation coming from the heliostat field can be deflected downwards by a mirror.

[0098] DLR-4347WO

[0099] 2025-12-22 Other directions, not shown, are also conceivable from which solar radiation falls onto the inclined plane 130. Additionally or alternatively, embodiments of the absorber device 100, not shown, are also conceivable, which have several radiation inlet openings 192.

[0100] As can be further seen from Figure 3, an angle of inclination β, shown in Figure 5, between the support surfaces 136 of the steps 134 and the horizontal plane HE is chosen such that a first proportion of the solid particles 182 remains on the support surfaces 136 of the respective steps 134, so that the first proportion of the solid particles 182 forms a particle bed. A second proportion of the solid particles 184 moves across the particle bed.

[0101] The solid particles 180 are heated to high temperatures, especially temperatures above 1000°C, by the concentrated solar radiation entering through the radiation inlet opening 192 as they move down the steps 134 or remain on the steps 134.

[0102] As can be further seen from Figure 1, the illustrated embodiment of the absorber device 100 according to the invention comprises a closed housing 190 in which the inclined plane 130 is arranged. The closed housing 190 surrounds a cavity. The closed housing 190 has at least one radiation inlet opening 192 for the concentrated solar radiation. Furthermore, the housing 190 includes a particle feed 110 for the solid particles 180. In addition, the housing 190 has the particle discharge area 160.

[0103] As can be further seen from Figure 1, in the illustrated embodiment of the absorber device 100 according to the invention, at least one distributor 120 is arranged above the at least one metering area 132, which distributes the solid particles 180 to the at least one metering area 132. The distributor 120 can form at least one inlet 122. In the illustrated embodiment, the particle feed 110 is designed as a pipe that feeds the solid particles 180 to the distributor 120. The distributor 120 has at least one distributor outlet, which forms at least one inlet 122. This inlet 122 is assigned to a corresponding metering area 132.

[0104] DLR-4347WO

[0105] 2025-12-22 In an alternative embodiment of the absorber device 100 according to the invention, not shown, the particle feed 110, which is designed as a tube, can be arranged above the at least one metering area 132 instead of the distributor 120. Here, the particle feed 110 forms the at least one inlet 122, which is assigned to at least one corresponding metering area 132.

[0106] As can be further seen from Figure 1, the inclined plane 130 is designed to be movable in the horizontal direction, in particular in the longitudinal direction x. This movement allows a horizontal distance b between a rotation axis DA and one of the inlets 122 to be set.

[0107] In the illustrated embodiment, a drive element moves the inclined plane 130 in the longitudinal direction x perpendicular to the vertical direction z via a coupling 140. This movement, and in particular the acceleration of the inclined plane 130, conveys the solid particles 180 down the steps 134 in the illustrated embodiment. In addition to the forces acting down the slope, the force of the drive element also acts on the solid particles 180. This movement of the inclined plane 130 in the longitudinal direction x can be reversed, allowing the corresponding forces to act in the appropriate direction. This prevents the particle movement from accelerating continuously. The flow velocity of the solid particles 180 thus reaches a value that oscillates around a constant value and does not increase continuously as it would on a simple inclined plane due to the sliding of the solid particles 180.Furthermore, the flow rate can be controlled and adjusted by the movement in the longitudinal direction x.

[0108] A driving motion of the inclined plane 130 in the longitudinal direction x or the corresponding counter-motion can be a periodic motion, in particular a sinusoidal motion. As can be seen from Figure 6, the duration of the period P affects the mass flow rate MS and / or the residence time t of the solid particles 180. In addition, the duration of the period P affects the maximum acceleration B of the inclined plane 130.

[0109] DLR-4347WO

[0110] 2025-12-22 An initial position for the periodic motion of the inclined plane 130 can be determined by the horizontal distance b between the axis of rotation DA and one of the inlets 122. Furthermore, the position of the cone of material on the inclined plane, which forms below the inlet, can be determined by the horizontal distance between an axis of rotation DA and one of the inlets 122.

[0111] Figure 6 shows three diagrams, with the period P, measured in seconds, plotted on the x-axis in all diagrams. In the top diagram, the mass flow rate MS of the solid particles 180 is plotted on the y-axis. In the middle diagram, the residence time t of the solid particles 180 is plotted on the y-axis, where t stands for mean residence time and is given in seconds. In the bottom diagram, the maximum acceleration B, as a fraction of the acceleration due to gravity g, is plotted on the y-axis.

[0112] Figure 6 shows the following: The longer the period P, the greater the residence time t of the solid particles 180 and the lower the mass flow rate MS of the solid particles 180. Although the period can be used to adjust the mass flow rate MS by reducing the period, in the illustrated embodiment it is primarily used to adjust the residence time t. The mass flow rate MS is adjusted in the illustrated embodiment by the distance b between the axis of rotation DA and one of the inlets 122, as shown in Figure 4, since shortening the period increases the maximum acceleration B of the inclined plane 130. In the illustrated embodiment, an acceleration of the inclined plane 130 of no more than 10% of the acceleration due to gravity is targeted.

[0113] In an alternative embodiment, the mass flow rate MS can also be adjusted via the distance a shown in Figure 4 between the metering areas 132 and the corresponding inlets 122.

[0114] DLR-4347WO

[0115] 2025-12-22 As can be further seen from Figure 1, the illustrated embodiment of the absorber device 100 according to the invention comprises at least one first adjusting element 150. The at least one first adjusting element 150 sets the inclination angle α of the inclined plane 130. In the illustrated embodiment, the first adjusting element 150 adjusts the inclined plane 130 such that the solid particles 180 just do not slip off. The mass flow rate MS is adjusted in the illustrated embodiment by the drive element and via the coupling 140, which moves the inclined plane 130 in the longitudinal direction x perpendicular to the vertical direction z. This movement in the longitudinal direction x also changes the relative position of the inclined plane 130 and thus also the relative position of the metering area 132 to the inlet 122, whereby the mass flow rate MS of the solid particles 180 can also be adjusted.Furthermore, as already described, the flow rate of the solid particles 180 can be adjusted by moving the inclined plane 130 in the longitudinal direction x, which also changes the mass flow rate MS accordingly.

[0116] Figure 7 shows the relationship between the inclination angle a of the inclined plane 130 and the mass flow rate MS of the solid particles 180, as well as between the inclination angle a of the inclined plane 130 and the residence time t of the solid particles 180.

[0117] Figure 7 shows two diagrams, where the angle of inclination α of the inclined plane 130, given in °, is plotted on the x-axis in all diagrams. In the uppermost diagram, the mass flow rate MS of the solid particles 180 is plotted on the y-axis. In the lower diagram, the residence time t of the solid particles 180, in seconds, is plotted on the y-axis.

[0118] Both diagrams show two curves. One curve marked with crosses was recorded with a period of 0.449 s. The other curve marked with circles was recorded with a period of 0.634 s.

[0119] DLR-4347WO

[0120] 2025-12-22As can be seen from the diagrams, a longer period leads to a smaller mass flow MS of the solid particles 180 and to a longer residence time t of the solid particles 180.

[0121] As can be seen from the diagrams, an increase in the inclination angle α leads to a larger mass flow rate MS of the solid particles 180. Furthermore, an increase in the inclination angle α leads to a reduced residence time t of the solid particles 180. From an inclination angle α of approximately 32°, the period has only a minor to no influence on the residence time t of the solid particles 180.

[0122] In the illustrated embodiment, a drive 152 actuates the adjusting element 150 depending on the temperature of the solid particles 180. Alternatively, the drive 152 can also actuate the adjusting element depending on the temperature in the cavity surrounded by the housing 190. In a further embodiment, the drive 152 can also actuate the adjusting element 150 depending on a predetermined residence time t of the solid particles 180 and / or a predetermined mass flow rate MS of the solid particles 180.

[0123] The drive 152 can be designed as a stepper motor and the at least one first adjusting element 150 can be designed as a toggle lever mechanism. During operation, a slight adjustment of the inclination angle α by a few degrees can be implemented during the heating process of the absorber device 100 according to the invention in order to react to the coefficient of friction of the solid particles 180 and the stages 134, which changes with temperature.

[0124] For example, in one type of solid particle, the friction of the solid particles 180 can increase with temperature, and experiments have shown that this results in a decrease in the flow velocity at a constant inclination of the inclined plane 130. In such a case, the angle of inclination α of the inclined plane 130 can be increased to compensate for the increased coefficient of friction. The friction of the solid particles 180 depends, among other things, on the material and shape of the solid particles 180.

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[0126] As can be further seen from Figure 7, the periods of movement of the inclined plane in the longitudinal direction x can be reduced by increasing the inclination angle a of the inclined plane 130 while keeping the residence time t and / or mass flow rate MS constant. This also allows the accelerations transmitted from the drive element via the coupling 140 to the inclined plane 130 for transporting the solid particles 180 to be significantly reduced.

[0127] In the illustrated embodiment, the inclination angle α is set to a point below the point at which the solid particles 180 would slide off on their own, and the sliding of the solid particles 180 is achieved by the movement or acceleration of the inclined plane 130 in the longitudinal direction x. This makes uncontrolled, avalanche-like sliding of the solid particles 180 more difficult or impossible.

[0128] In an embodiment not shown, which only has the first adjusting element 150 for adjusting the inclination angle a, the movement or acceleration of the solid particles 180 and thus the mass flow MS and / or the residence time t can be adjusted by adjusting the inclination angle a and the corresponding downslope force.

[0129] In an embodiment which only has the drive element which moves the inclined plane 130 in the longitudinal direction x perpendicular to the vertical direction z via the coupling 140, the movement or acceleration of the solid particles 180 and thus the mass flow MS and / or the residence time t can be adjusted by setting the period of the corresponding movement of the inclined plane in the longitudinal direction x, in particular together with the zero point of this movement defined by the distance b.

[0130] As can be further seen from Figure 2, the steps 134 in the illustrated embodiment of the absorber device 100 according to the invention are formed from bands 135 arranged transversely to the inclination direction N. The bands 135 consist in particular of aluminium oxide.

[0131] DLR-4347WO

[0132] 2025-12-22 The inclination direction N corresponds to the flow direction of the solid particles 180. The aluminum oxide strips 135 are narrow in the inclination direction N and in the longitudinal direction x, and therefore expand primarily in the direction transverse to the inclination direction N and in the transverse direction y under thermal stress, thus reducing thermomechanical stresses. In the illustrated embodiment, the steps 134 are formed from commercially available, dense aluminum oxide ceramic strips. The strips 135 can also be formed from other suitable heat-resistant materials, for example, zirconium oxide or silicon carbide.

[0133] As can be further seen from Figure 2, the illustrated embodiment of the absorber device 100 according to the invention comprises a holding arrangement 138. This holding arrangement 138 holds the bands 135.

[0134] In the illustrated embodiment, the holding assembly 138 comprises two components made of aluminum silicate with a high aluminum oxide content. These components can be designed as porous vacuum-formed parts. The components of the holding assembly 138 can also be made of other suitable heat-resistant materials. The strips 135 are clamped between these components. Other methods of securing the strips 135 besides clamping are also conceivable. The clamping action results in a positive and / or force-fit connection between the strips 135 and the holding assembly 138. Due to the strip geometry, thermal expansion occurs essentially one-dimensionally in the transverse direction y, thereby reducing thermomechanical stresses. In particular, the holding assembly 138 allows thermal expansion in the transverse direction y, while the strips 135 simultaneously exhibit minimal play in the vertical direction z and the longitudinal direction x.

[0135] As can be seen from Figures 3 to 5, the bearing surfaces 136 of the steps 134 have an inclination with the angle of inclination β to the horizontal plane HE. β corresponds to the angle between the horizontal plane HE perpendicular to the vertical direction z and the corresponding bearing surface 136. The angle of inclination y of the bearing surfaces 136 of the steps 134 is arranged between the inclined plane 130 and the bearing surface 136.

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[0137] 2025-12-22 In the illustrated embodiment, the angle of inclination y of the bearing surfaces 136 of the steps 134 to the inclined plane 130 is smaller than the angle of inclination α of the inclined plane 130. However, it is also possible that the angle of inclination β between the horizontal plane HE and the corresponding bearing surface 136 is negative, in which case the angle of inclination y of the bearing surfaces 136 of the steps 134 to the inclined plane 130 is greater than the angle of inclination α of the inclined plane 130 to the horizontal plane HE. For example, the angle of inclination β of the bearing surfaces 136 to the horizontal plane HE can be between -5° and 10°.

[0138] Figure 8 shows the relationship between the inclination angle β and the mass flow rate MS of the solid particles 180 as well as the relationship between the inclination angle β and the residence time t of the solid particles 180.

[0139] Figure 8 shows two diagrams, where the inclination angle β, given in °, is plotted on the x-axis in all diagrams. In the uppermost diagram, the mass flow rate MS of the solid particles 180 is plotted on the y-axis. In the lower diagram, the residence time t of the solid particles 180, in seconds, is plotted on the y-axis.

[0140] Both diagrams show two curves. One curve, indicated by a solid line, was recorded at a first distance b between the axis of rotation DA and the inlet 122. The other curve, indicated by a dashed line, was recorded at a second distance b between the axis of rotation DA and the inlet 122. The first distance b is smaller than the second distance b.

[0141] As can be seen from the diagrams, a smaller distance b between the axis of rotation DA and the inlet 122 leads to a smaller mass flow MS of the solid particle 180 and to a longer residence time t of the solid particle 180.

[0142] DLR-4347WO

[0143] 2025-12-22 As can be seen from the diagrams, an increase in the tilt angle β leads to a larger mass flow rate MS of the solid particles 180. Furthermore, an increase in the tilt angle β leads to a reduced residence time t of the solid particles 180.

[0144] As the angle of inclination β increases, the support surface 136 aligns itself towards the inclined plane 130, thereby increasing the mass flow rate MS of the solid particles 180 and decreasing the residence time t of the solid particles 180. The shape of the first stage has the greatest influence on the mass flow rate MS of the solid particles 180. Due to the angle of inclination β, a larger cross-section for the solid particles 180 is created in the dosing area 132, allowing them to flow out of the inlet pipe 122. At the other stages, increasing the angle of inclination β primarily leads to an increase in the flow velocity and a decrease in the residence time t.

[0145] The profiles shown in Figures 6, 7, and 8 apply to one type of solid particle. Naturally, the profiles may vary if other solid particles 180 with different shapes, sizes, weights, and / or made of a different material are applied to the inclined plane 130.

[0146] Optionally, in the embodiment shown in Figures 1 and 4 of the absorber device 100 according to the invention, a second, unspecified adjusting element may be provided which adjusts the vertical distance a between the at least one inlet 122 and the at least one metering area 132.

[0147] As can be seen in Figure 8, the distance b influences the mass flow rate MS of the solid particles 180 and the residence time t of the solid particles 180. A larger distance b can increase the mass flow rate MS of the solid particles 180. A larger distance b can reduce the residence time t of the solid particles 180.

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[0149] 2025-12-22 As can be further seen from Figure 1, Figure 9 and Figure 10, in the illustrated embodiment of the absorber device 100 according to the invention, a radiation blocking barrier 170 is arranged below the inclined plane 130. This prevents heat losses and radiation losses from occurring when the angle of inclination α changes.

[0150] As can be seen from Figures 9 and 10, the radiation blocking barrier 170 allows movement of the inclined plane 130. The radiation blocking barrier 170 prevents a direct optical path between hot inner surfaces of the cavity in the housing 190 and colder surfaces and / or the colder environment outside the housing 190. The radiation blocking barrier 170 is formed by two interlocking lamellar structures 172. This results in a meandering path for the radiation. If the gaps between the lamellar structures 172 are very small, the radiation losses are therefore low.

[0151] In a method for operating an absorber device 100 according to the invention, which is not described in detail, the following steps are carried out. The solid particles 180 are transferred to at least one metering area 132 on an inclined plane 130, which is provided for transporting the solid particles 180 and comprises several stages 134. The stages 134 each have a support surface 136, which are spaced apart by a distance 137 in the vertical direction z. In a further step, a region of the inclined plane 130 and the solid particles 180 located thereon are irradiated with concentrated solar radiation. The solid particles 180 are moved, among other things, by the inclination of the inclined plane 130 from the at least one metering area 132 to a particle discharge area 160.The inclination of the support surfaces 136 of the steps 134 relative to the horizontal plane HE with an angle of inclination β is chosen such that a first proportion of the solid particles 182 remain on the support surfaces 136 of the respective steps 134 and form a particle bed. A second proportion of the solid particles 184 move across the particle bed.

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[0153] 2025-12-22Reference number

[0154] 100 absorber device

[0155] 110 particle feed

[0156] 120 distributors

[0157] 122 Admission

[0158] 130 Inclined Plane

[0159] 132 Dosing area

[0160] 134 steps

[0161] 135 ceramic band

[0162] 136 contact area

[0163] 137 Distance in the vertical direction

[0164] 138 Holding arrangement

[0165] 140 Coupling to the drive unit for the inclined plane

[0166] 150 setting element

[0167] 152 Drive

[0168] 160 Particle removal area outlet

[0169] 170 Radiation blockage

[0170] 180 solid particles

[0171] 184 flowing solid particles

[0172] 182 stationary solid particles

[0173] 190 cases

[0174] 192 a radiation inlet opening

[0175] a) Angle of inclination of the inclined plane to the horizontal plane β) Angle of inclination of the support surfaces to the horizontal plane Y) Angle of inclination of the support surfaces to the inclined plane z) Vertical direction

[0176] x Longitudinal direction

[0177] y transverse direction

[0178] HE horizontal plane

[0179] N Inclination direction

[0180] a) vertical distance between inlet and metering area b) horizontal distance between axis of rotation and inlet DA axis of rotation

[0181] P Period

[0182] MS Mass Flow

[0183] t Stay time

[0184] B maximum acceleration of the inclined plane

[0185] DLR-4347WO

[0186] 2025-12-22

Claims

Claims 1. Absorber device (100) in which solid particles (180) are heated by concentrated solar radiation, comprising an inclined plane (130) which is provided for transporting the solid particles (180) and which has at least one metering area (132) and several stages (134), wherein the steps (134) each have a support surface (136) which are each spaced apart by a distance (137) in the vertical direction (z), wherein the solid particles (180) hit the inclined plane (130) on the at least one metering area (132) and move from the at least one metering area (132) to a particle removal area (160), wherein the concentrated solar radiation is directed onto at least one area of ​​the inclined plane (130) and heats the solid particles (180) in this area, wherein an inclination angle (β) of the bearing surfaces (136) of the steps (134) relative to a horizontal plane (HE) is chosen such that a first proportion of the solid particles (182) remains on the bearing surfaces (136) of the respective steps (134), and the first proportion of the solid particles (182) forms a particle bed, and wherein a second proportion of the solid particles (184) moves across the particle bed.

2. Absorber device (100) according to claim 1, wherein the inclined plane (130) is designed to be movable in a horizontal direction, in particular in the longitudinal direction (x), and / or wherein a horizontal distance (b) between the axis of rotation (DA) and the inlet (122) is designed to be adjustable, in particular wherein the distance (b) influences the mass flow (MS) of the solid particles (180). DLR-4347WO 2025-12-223. Absorber device (100) according to claim 2, wherein a driving movement of the inclined plane (130) in a horizontal direction, in particular in the longitudinal direction (x), is a periodic movement, in particular a sinusoidal movement, wherein the mass flow rate (MS) of the solid particles (180) and / or the residence time (t) of the solid particles (180) are adjustable by the duration of the period (P).

4. Absorber device (100) according to one of the preceding claims, wherein at least one first adjusting element (150) is provided which adjusts the inclination angle (a) of the inclined plane (130), in particular wherein a drive (152) drives the adjusting element (150) depending on a temperature of the solid particles (180).

5. Absorber device (100) according to one of the preceding claims, wherein a distance (a) between at least one inlet (122) and the at least one metering area (132) is adjustable, in particular wherein the distance (a) influences the mass flow (MS) of the solid particles (180).

6. Absorber device (100) according to one of the preceding claims, wherein at least one distributor (120) is arranged above the at least one metering area (132), which distributes the solid particles (180) onto the at least one metering area (132), in particular wherein the distributor (120) forms the at least one inlet (122).

7. Absorber device (100) according to one of the preceding claims, wherein the steps (134) are formed from bands (135) arranged transversely to the inclination direction (N), in particular from aluminium oxide.

8. Absorber device (100) according to claim 7, wherein a holding arrangement (138) with at least two components, in particular porous vacuum-formed parts made of aluminium silicate with a high proportion of aluminium oxide, holds the strips (135) in a form-fitting and / or force-fitting manner. DLR-4347WO 2025-12-229. Absorber device (100) according to one of the preceding claims, wherein the angle of inclination (β) between the support surfaces (136) and the horizontal plane (HE) is between -5° and +10°.

10. Absorber device (100) according to one of the preceding claims, wherein the inclined plane (130) is arranged in a closed housing (190) which has at least one radiation inlet opening (192) for concentrated solar radiation, and the particle removal area (160).

11. Absorber device (100) according to one of the preceding claims, wherein a radiation blocking device (170) is arranged below the inclined plane (130).

12. Method for operating an absorber device (100) according to one of the preceding claims, with the following steps: transferring the solid particles (180) to at least one metering area (132) on an inclined plane (130) which is provided for the transport of the solid particles (180) and comprises several stages (134), each of which has a support surface (136) which is spaced apart by a distance (137) in the vertical direction (z), Irradiation of an area of ​​the inclined plane (130) and the solid particles (180) located thereon with concentrated solar radiation, wherein the solid particles (180) are moved from at least one metering area (132) to a particle removal area (160), wherein an inclination (β) of the support surfaces (136) of the steps (134) is selected relative to the horizontal plane (HE) such that a first proportion of the solid particles (182) remains on the support surfaces (136) of the respective steps (134) and forms a particle bed, wherein a second proportion of the solid particles (184) moves over the particle bed. DLR-4347WO 2025-12-22

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