METHOD FOR OPERATING AN ABSORPTION DEVICE AND ABSORPTION DEVICE

Abstract

A method for operating an absorber device for absorbing carbon dioxide from a gas stream is described. The method comprises the steps of contacting an absorbent with the gas stream within an absorption volume, generating a loaded absorbent, depositing at least a portion of the loaded absorbent in the absorption volume, and removing the deposited portion of the loaded absorbent from the absorption volume by means of a cleaning element. Furthermore, an absorber device is specified.

Description

[0001] A method for operating an absorber device and an absorber device are specified.

[0002] The task is to provide an efficient method for operating an absorber device. Furthermore, a more efficient absorber device should be provided.

[0003] According to at least one embodiment, a method for operating an absorber device is described. In particular, the method is designed for absorbing carbon dioxide from a gas stream. The gas stream is, for example, air. The absorber device can be a device in which the absorption of carbon dioxide from the gas stream is carried out.

[0004] According to at least one embodiment of the method, an absorbent is brought into contact with the gas stream within an absorption volume. In particular, the absorbent is a mixture designed to absorb carbon dioxide from the gas stream. The absorbent comprises or consists, for example, of a mixture of components. The absorption volume is, for example, a volume in which absorption of carbon dioxide from the gas stream takes place. The absorption volume can be a reactor.

[0005] According to at least one embodiment of the method, a loaded absorbent is produced. The loaded absorbent is produced, in particular, by absorbing carbon dioxide from the gas stream. In other words, the loaded absorbent comprises absorbed carbon dioxide.

[0006] According to at least one embodiment of the method, at least a portion of the loaded absorbent is deposited in the absorption volume. In this way, a deposited portion of the loaded absorbent is formed. In particular, the deposited portion of the loaded absorbent is a compound resulting from the absorption of carbon dioxide. This portion of the loaded absorbent is deposited, for example, on structures such as grids provided in the absorption volume. The deposited portion of the loaded absorbent can comprise or consist of crystals of a compound resulting from the absorption of carbon dioxide.

[0007] Advantageously, separating part of the loaded absorbent can increase the absorption rate, as it prevents supersaturation of the loaded absorbent. This reduces the inhibition of further carbon dioxide absorption.

[0008] According to at least one embodiment of the method, the deposited portion of the loaded absorbent is removed from the absorption volume, in particular by means of a cleaning element. Here and in the following, a cleaning element is a means for removing the deposited portion of the loaded absorbent. The cleaning element is, for example, a self-cleaning surface or a device for mechanically removing the deposited portion of the loaded absorbent.

[0009] According to at least one embodiment, the method for operating the absorber device for absorbing carbon dioxide from the gas stream comprises the following steps: - Bringing the absorbent into contact with the gas stream within the absorption volume, - Preparation of the loaded absorbent, - Separation of at least a portion of the loaded absorbent in the absorption volume, - Removal of the separated part of the loaded absorbent from the absorption volume using the cleaning element.

[0010] It is an idea of ​​the present disclosure to provide a method for operating an absorber device that enables carbon dioxide absorption with an absorbent, optionally a suspension, comprising a high degree of supersaturation. A high degree of supersaturation in the absorbent can be desirable because it can increase the effectiveness of the crystallization process. On the other hand, the high degree of supersaturation in the absorbent leads to a high degree of crystal contamination in the absorption volume, for example, on a packing material within the absorption volume. However, by removing the deposited portion of the loaded absorbent, clogging within the absorption volume and / or a pressure drop in the gas flow due to crystal contamination can be prevented. This advantageously increases the efficiency of the carbon dioxide absorption and thus the method for operating the absorber device.

[0011] Furthermore, by removing the deposited portion of the loaded absorbent using a purification element, the removal of the deposited portion of the loaded absorbent by dissolution and subsequent recrystallization can be avoided. In addition, the described method offers the possibility of maintaining a high degree of supersaturation, particularly of the loaded absorbent, in the absorber device.

[0012] Additional crystallization steps are particularly costly, as they require investment in the appropriate equipment, an increased volume of absorbent, and active cooling of the crystallizer. The method described here for operating the absorber device is therefore advantageously characterized by lower operating costs and lower investment costs compared to other methods.

[0013] According to at least one embodiment of the method, the absorbent comprises a metal carbonate. In particular, the absorbent comprises a mixture of the metal carbonate and water. It is also possible that the absorbent comprises additional carbon dioxide-absorbing compounds, which may form part of the deposited portion of the loaded absorbent.

[0014] According to at least one embodiment of the process, the metal carbonate is at least partially converted into a metal hydrogen carbonate during the production of the loaded absorbent. In particular, the metal hydrogen carbonate is generated by the absorption of carbon dioxide. The deposited portion of the loaded absorbent, especially the crystals, comprises or consists, for example, of the metal hydrogen carbonate. The metal of the metal carbonate and / or the metal hydrogen carbonate is, for example, an alkali metal such as potassium. In contrast to other monovalent metals, potassium is advantageously used as the metal of the metal carbonate and / or as the metal of the metal hydrogen carbonate because it is particularly suitable as the only crystal modification that forms stable potassium hydrogen carbonate over the entire concentration and pressure range used in the process.Furthermore, it was surprisingly discovered that potassium bicarbonate, compared to sodium bicarbonate, exhibits low adhesion of the deposited loaded absorbent in the absorption volume.

[0015] According to at least one embodiment of the method, the absorbent is provided as a suspension. A suspension is a heterogeneous mixture of a liquid and solid particles. Advantageously, providing the absorbent as a suspension allows for a high crystal surface area, which promotes the reduction of supersaturation through crystal growth rather than crystal formation and / or crystal nucleation. This ensures efficient supersaturation reduction and a high mass transfer rate of carbon dioxide into the absorbent due to a lower concentration of metal bicarbonate in the loaded absorbent. Furthermore, the risk of immediate crystallization, for example, as a result of nucleation, is reduced.

[0016] According to at least one embodiment of the method, the absorber device comprises a distributor. In particular, the distributor provides the absorbent within the absorption volume. The distributor is, for example, a rotary distributor or a drip distributor. Advantageously, a rotary distributor can offer a high degree of variability in the flow rate at which the absorbent is supplied. Furthermore, the rotary distributor can accommodate an absorbent in the form of a suspension.

[0017] In particular, the distributor includes inserts that can define a distribution cone of the absorbent within the absorption volume. The distribution cone of the absorbent corresponds, for example, to the distribution angle of the absorbent within the absorption volume. Advantageously, the inserts can be adjusted to counteract changes in the viscosity of the absorbent in order to maintain a uniform distribution cone. Thus, the inserts enable a uniform distribution even when the temperature changes, for example, due to seasonal variations.

[0018] It is also possible to adjust the distribution cone using a motor to drive the distributor, especially a rotary distributor. For example, the distribution cone is adjusted by changing the speed at which the motor drives the rotary distributor.

[0019] According to at least one embodiment of the method, the distributor is operated at a first flow rate to supply the absorbent to the absorption volume. The distributor is operated at a second flow rate to remove the deposited portion of the loaded absorbent, particularly in addition to supplying the absorbent within the absorption volume. In particular, the second flow rate is higher than the first flow rate. In the present embodiment, the distributor can perform two functions: supplying the absorbent and acting as a cleaning element. Thus, advantageously, no additional elements need to be provided in the absorption device to act as a cleaning element.

[0020] According to at least one embodiment of the method, removing the deposited portion of the loaded absorbent comprises removing the deposited portion of the loaded absorbent with a cleaning solution provided by the cleaning element. In particular, the cleaning solution is provided by the distributor, especially the rotary distributor, or by spray nozzles within the absorption volume. The cleaning solution is, for example, a solution that can be obtained after regeneration of the loaded absorbent, particularly at elevated temperatures. The cleaning solution can be provided at the elevated temperatures. Elevated temperatures here and in the following correspond in particular to a temperature of at least 40 °C, at least 50 °C, or at least 60 °C.An increased temperature and / or a cleaning solution containing a low concentration of metal bicarbonate can enable efficient removal of the deposited portion of the loaded absorbent.

[0021] According to at least one embodiment of the method, the removal of the deposited portion of the loaded absorbent comprises the removal of the deposited portion of the loaded absorbent by means of an external oscillating excitation provided by the cleaning element. In particular, the deposited portion of the loaded absorbent is removed by a mechanical force provided by the cleaning element. In the present embodiment, the cleaning element comprises, for example, a vibration unit or consists thereof.

[0022] Furthermore, an absorber device is disclosed. In particular, the absorber device is used in the method described herein for operating an absorber device for absorbing carbon dioxide from a gas stream. Therefore, the embodiments, features, and advantages disclosed in connection with the method also apply to the absorber device, and vice versa.

[0023] According to at least one embodiment, the absorption device is designed to be used for absorbing carbon dioxide from a gas stream.

[0024] According to at least one embodiment, the absorber device comprises an absorption volume for an absorbent. The absorber device further comprises a cleaning element. In particular, the cleaning element is arranged within the absorption volume. Additionally or alternatively, the cleaning element is arranged outside the absorption volume. The absorber device can comprise more than one cleaning element, for example, two or three. In this case, the cleaning elements differ from one another, for example, with regard to their arrangement inside or outside the absorption volume.

[0025] According to at least one embodiment of the absorber device, the absorption volume is configured to bring the absorbent into contact with the gas stream, so that a loaded absorbent is produced and a portion of the loaded absorbent is deposited, particularly within the absorption volume. The absorption volume comprises, for example, a grid structure and / or a packing material along which the absorbent can flow.

[0026] The absorbent specifically comprises a metal carbonate. Upon absorption of carbon dioxide from the gas stream, the metal carbonate is converted into a metal hydrogen carbonate. In this case, the deposited portion of the loaded absorbent can comprise or consist of the metal hydrogen carbonate.

[0027] According to at least one embodiment of the absorber device, the cleaning element is configured to remove the deposited portion of the loaded absorbent from the absorption volume. In particular, the cleaning element is designed or configured to actively or passively remove the deposited portion of the loaded absorbent from the absorption volume. "Active removal" here and in the following means that the cleaning element removes the deposited portion of the loaded absorbent, for example, by a mechanical force provided by the cleaning element. "Passive removal" here and in the following means that the cleaning element is configured such that the deposited portion of the loaded absorbent is removed from the absorption volume, for example, due to reduced adhesion to a surface within the absorption volume.

[0028] According to at least one embodiment, the absorber device for absorbing carbon dioxide from a gas stream comprises the absorption volume for the absorbent and the cleaning element, wherein the absorption volume is configured to bring the absorbent into contact with the gas stream so that the loaded absorbent is produced and the portion of the loaded absorbent is deposited, and wherein the cleaning element is configured to remove the deposited portion of the loaded absorbent from the absorption volume.

[0029] One idea is to incorporate a cleaning element into the absorber device to prevent clogging within the absorption volume caused by the deposited portion of the loaded absorbent. Furthermore, by removing this deposited portion, the cleaning element helps maintain the carbon dioxide absorption efficiency of the absorber device, even during extended operating times. It is also advantageous that the absorber device can be operated with an absorbent in suspension form.

[0030] According to at least one embodiment of the absorber device, the cleaning element comprises a distributor configured to distribute the absorbent and / or a cleaning solution within the absorption volume. The distributor may include spray nozzles. In particular, the cleaning solution may be the same as the absorbent but supplied within the absorption volume at a different flow rate. The distributor may, for example, be a rotary distributor or a drip distributor. The rotary distributor can distribute the absorbent randomly within the absorption volume. Furthermore, the rotary distributor can allow for a low pressure drop.

[0031] According to at least one embodiment, the absorber device further comprises a distribution layer. In particular, the distribution layer is present when the absorber device includes the rotary distributor. For example, the distribution layer is located downstream of the distributor, especially the rotary distributor. For example, the distribution layer is a trickle screen. In particular, the distributor is designed such that crystal contamination does not occur within it. Crystal contamination is understood to mean, in particular, the deposition of macroscopic crystals or agglomerates, for example, of the loaded absorbent, which can negatively affect the functionality of the absorber device.

[0032] Advantageously, the distribution layer homogenizes the distribution of the absorbent within the absorption volume. In other words, the distribution layer transforms chaotic droplets originating from the distributor, particularly the rotary distributor, into a uniform film. This prevents the absorbent from falling through channels in a packing material within the absorption volume. Additionally or alternatively, the distributor provides a cost-effective way to distribute the absorbent homogeneously within the absorption volume. Furthermore, the distribution layer advantageously exhibits only a minimal pressure drop.

[0033] According to at least one embodiment of the absorber device, the cleaning element comprises or consists of self-cleaning surfaces. In particular, self-cleaning surfaces are a cleaning element that passively removes the deposited portion of the loaded absorbent. The self-cleaning surfaces are, for example, arranged on a surface of the packing material within the absorption volume. The self-cleaning surfaces comprise or consist, for example, of a fluorinated polymer such as ethylenetetrafluoroethylene (ETFE).

[0034] Advantageously, large quantities of the deposited, loaded absorbent cannot remain on the self-cleaning surfaces for extended periods. This can cause the deposited, loaded absorbent to flake off and collect at the bottom of the absorber device.

[0035] According to at least one embodiment of the absorber device, the cleaning element comprises a grid structure, the grid structure being configured to release the deposited portion of the loaded absorbent at a predetermined thickness. The predetermined thickness of the deposited portion of the loaded absorbent is, in particular, at least 50 micrometers or at least 100 micrometers. The thickness is determined, for example, for the deposited portion of the loaded absorbent on the grid structure. The grid structure is, for example, arranged within the absorption volume.

[0036] According to at least one embodiment of the absorber device, the cleaning element comprises or consists of spray nozzles. The spray nozzles are, in particular, part of the distributor. Additionally or alternatively, the spray nozzles are a further element of the absorber device. The spray nozzles are, for example, arranged and designed to remove the deposited portion of the loaded absorbent. The spray nozzles serve, for example, to remove the deposited portion of the loaded absorbent from the grid structure or the packing material in the absorption volume. The spray nozzles are, for example, arranged at an angle, for example perpendicular, to the flow direction of the absorbent. The angle can be less than 180° and more than 0°, or at most 150° and at least 30°.

[0037] According to at least one embodiment of the absorber device, the cleaning element is designed to remove the deposited portion of the loaded absorbent from the absorption volume by means of external oscillating excitation. In particular, the cleaning element comprises a vibration unit. The external oscillating excitation can exert a mechanical force on the deposited portion of the loaded absorbent. In this way, the deposited portion of the loaded absorbent breaks off, for example, from the grid structure or the packing material.

[0038] According to at least one embodiment of the absorber device, the absorption volume comprises an upper absorption layer and a lower absorption layer. In particular, the upper absorption layer is arranged closer to the distributor than the lower absorption layer. For example, the upper absorption layer and the lower absorption layer differ in their structure. The main absorption of carbon dioxide in the absorbent takes place in the upper and lower absorption layers. Advantageously, the upper absorption layer and / or the lower absorption layer are configured to achieve an optimum mass transfer rate of carbon dioxide into the absorbent. In particular, the gas flows in one direction, from the lower absorption layer to the upper absorption layer.

[0039] According to at least one embodiment of the absorber device, the upper absorption layer comprises a packing material. In particular, the packing material comprises or consists of a plastic. The packing material is, for example, structured. The packing material is arranged such that falling particles of the deposited portion of the loaded absorbent are not blocked. For example, the packing material is flexible. This advantageously enables efficient removal of the deposited portion of the loaded absorbent by external oscillating excitation.

[0040] The packing material increases the surface area of ​​the absorbent within the absorption volume. This advantageously improves the efficiency of carbon dioxide absorption from the gas stream. Furthermore, the packing material can be used to crystallize the loaded absorbent. This eliminates the need for a separate crystallization step and / or a crystallization tank.

[0041] In particular, the portion of the loaded absorbent within the absorption volume is deposited on the packing material; for example, this portion crystallizes on the packing material. The portion of the loaded absorbent deposited on the packing material advantageously improves the wetting of the packing material, which can enhance the carbon dioxide absorption efficiency. This allows the use of a plastic packing material instead of an expensive stainless steel one.

[0042] According to at least one embodiment of the absorber device, the packing material comprises a corrugated or open structure. Advantageously, a packing material with such a structure can improve absorption efficiency while ensuring that the removed portions of the deposited portion of the loaded absorbent do not block the packing material.

[0043] According to at least one embodiment of the absorber device, the lower absorption layer comprises a packing material. In particular, the packing material of the lower absorption layer is optimized to prevent or improve the deposition of the loaded absorbent, for example, by reducing crystal contamination. The lower absorption layer may include self-cleaning surfaces, for example, for easy removal of the deposited portion of the loaded absorbent. Furthermore, spray nozzles may be arranged on the sides of the lower absorption layer, particularly to further improve the removal of the deposited portion of the loaded absorbent.

[0044] According to at least one embodiment of the absorber device, the packing material, in particular the lower absorption layer, comprises rough surfaces. Advantageously, the rough surfaces exhibit an improved deposition rate of the loaded absorbent.

[0045] According to at least one embodiment of the absorber device, the packing material, particularly of the lower absorption layer, comprises or consists of a material selected from the group consisting of ceramics, mineral materials, polymers, and combinations thereof. The mineral material is particularly structured or disordered. A packing material made of these materials can exhibit high adhesion for the deposited portion of the loaded absorbent. Additionally or alternatively, these materials are materials with high surface energy, which can improve the deposition rate of the loaded absorbent. In particular, such a packing material is arranged in the lower absorption layer.

[0046] According to at least one embodiment of the absorber device, the lower absorption layer comprises a trickle grid. Additionally or alternatively, the grid structure is arranged in the lower absorption layer and is designed to release the deposited portion of the loaded absorbent.

[0047] According to at least one embodiment of the absorber device, during operation of the absorber device, the specific mass transfer in the upper absorption layer is higher than in the lower absorption layer. In particular, the specific mass transfer is the mass transfer of carbon dioxide from the gas stream into the absorbent per unit absorption volume. The unit of specific mass transfer is mol / s·m³. 3 The specific mass transfer can be calculated from the mass transfer rate (unit: mol / m³). 2 ·s) can be determined with constant absorber geometries and specific packing properties.

[0048] The mass transfer rate decreases due to the decrease in carbon dioxide concentration in the direction of gas flow, as the mass transfer coefficient (unit: mol / m³) changes. 2 ·Pa CO2 The mass transfer coefficient (·s) is neglected with regard to a small change in the concentration of the absorbent throughout the entire absorption volume. For example, the gas flow is in one direction, from the lower absorption layer to the upper absorption layer. The mass transfer coefficient is defined as the mass transfer (mol) per unit area of ​​the packing (m²). 2 ) per carbon dioxide partial pressure (Pa CO2 ) per second (s).

[0049] In particular, the specific mass transfer from the upper absorption layer to the lower absorption layer decreases logarithmically. This logarithmic decrease can be counteracted by specific packing material properties and other process parameters.

[0050] The higher specific mass transfer in the upper absorption layer is achieved, for example, by increasing the specific packing surface area per volume element in the upper absorption layer. In other words, the upper absorption layer contains a packing material with a larger specific packing surface area per volume element than the packing material in the lower absorption layer.

[0051] The higher specific mass transfer in the upper absorption layer can also be achieved by flattening the flow angle of the absorbent from the lower to the upper absorption layer. This reduces the flow velocity of the absorbent, particularly at the packing surface, from the lower to the upper absorption layer. This can lead to an increase in contact time at a constant volume and thus, in particular, to an increase in the concentration of the loaded absorbent within the packing material.

[0052] According to at least one embodiment of the absorber device, the packing material in the upper absorption layer and / or the lower absorption layer is configured or designed to achieve homogeneous wetting. This can advantageously also lead to an optimization of the specific mass transfer, such that the specific mass transfer in the upper absorption layer is higher than in the lower absorption layer.

[0053] According to at least one embodiment of the absorber device, during operation the absorber device exhibits a higher deposition rate of the loaded absorbent in the lower absorption layer than in the upper absorption layer. Advantageously, this results in less or no clogging of the absorption volume by the deposited portion of the loaded absorbent. Additionally or alternatively, it is possible to remove the deposited portion of the loaded absorbent without reducing the carbon dioxide absorption efficiency.

[0054] According to at least one embodiment of the absorber device, the angle of inclination in the packing material within the absorption volume increases from the upper absorption layer to the lower absorption layer. In other words, the angle of inclination of the packing material is greater in the lower absorption layer than in the upper absorption layer. This allows the deposited portion of the loaded absorbent to be removed more easily by gravity and the shear forces acting on the absorbent. For example, the absorbent has a higher flow velocity at the packing material when the angle of inclination within the packing material is greater.

[0055] According to at least one embodiment of the absorber device, the specific surface area of ​​the packing material in the absorption volume decreases from the upper absorption layer to the lower absorption layer. In other words, the packing material is more densely packed in the upper absorption layer than in the lower absorption layer. This advantageously achieves optimal mass transfer of carbon dioxide into the absorbent throughout the entire absorption volume.

[0056] According to at least one embodiment of the absorber device, the hydrophilicity of the packing material increases from the lower absorption layer to the upper absorption layer. In other words, the hydrophobicity increases from the upper absorption layer to the lower absorption layer. This can also enable more efficient carbon dioxide absorption, as it results in an improved mass transfer rate of carbon dioxide into the absorbent.

[0057] According to at least one embodiment of the absorber device, the absorption volume, in particular the upper absorption layer and the lower absorption layer, is designed such that the retention time of the absorbent and / or the loaded absorbent decreases from the upper absorption layer to the lower absorption layer. This can also improve the efficiency of carbon dioxide absorption.

[0058] Advantageously, all the measures described here can lead to a reduction in the specific mass transfer at the lower absorption layer. At the same time, these measures also counteract high rates of crystal fouling. In other words, the method and absorber device described here make it possible to achieve increasing supersaturation of the absorbent from the upper to the lower absorption layer. Simultaneously, the absorber device can be configured, in particular, to reduce the deposition of the loaded absorbent in the absorption volume, especially in the lower absorption layer. This is achieved, for example, by the cleaning element.

[0059] Advantageous embodiments and further developments of the method for operating an absorber device and the absorber device are evident from the exemplary embodiments described below in conjunction with the figures.

[0060] In the characters: Fig. Figure 1 schematically shows the steps of a method for operating an absorber device according to an exemplary embodiment. Fig. Figure 2 shows a schematic cross-section of an absorber device according to an exemplary embodiment. The Fig. 3A and Fig. Figure 3B shows a specific mass transfer as a function of height in the absorption volume of an absorber device.

[0061] In the exemplary embodiments and figures, similar or similarly functioning components are designated with the same reference numerals. The elements depicted in the figures and their relative sizes are not to be considered to scale. Rather, individual elements may be shown in an exaggerated size for the purpose of better illustration and / or understanding.

[0062] Combined with Fig. Section 1 describes a method for operating an absorber device 1 according to an exemplary embodiment. The absorber device 1 is designed to absorb carbon dioxide from a gas stream.

[0063] In a first process step S1, an absorbent is brought into contact with the gas stream within an absorption volume 2 of the absorber device 1. The absorbent can be a suspension containing a metal carbonate, for example potassium carbonate. The absorbent is supplied to the absorption volume 2 by a distributor 3, in particular a rotary distributor or a drip distributor.

[0064] In a further process step S2, a loaded absorbent is produced by absorption of carbon dioxide in the absorbent. During the absorption of the carbon dioxide, the metal carbonate reacts at least partially to form a metal hydrogen carbonate.

[0065] Subsequently, in process step S3, at least a portion of the loaded absorbent is deposited in absorption volume 2. For example, the metal bicarbonate formed by carbon dioxide absorption is deposited in absorption volume 2. It is possible for the metal bicarbonate to precipitate in absorption volume 2. Additionally or alternatively, other components of the loaded absorbent can also be deposited in absorption volume 2. In particular, the loaded absorbent is deposited on a packing material 6 or a grid structure in absorption volume 2.

[0066] In process step S4, the deposited portion of the loaded absorbent is removed from the absorption volume by means of a cleaning element. The cleaning element can be a variety of different elements in the absorber device 1, which are configured to remove the deposited portion of the loaded absorbent from the absorption volume 2.

[0067] For example, distributor 3, in particular the rotary distributor, is used as a cleaning element. Distributor 3 is operated at a first flow rate to supply the absorbent to the absorption volume 2. To remove the deposited portion of the loaded absorbent, distributor 3 is operated at a second flow rate that is higher than the first. A cleaning solution or the absorbent itself can be used to remove the deposited portion of the loaded absorbent. The cleaning solution can be an undersaturated, regenerated absorbent produced by the desorption of carbon dioxide from the loaded absorbent. The cleaning solution can be supplied at temperatures of at least 40 °C, at least 50 °C, or at least 60 °C to remove the deposited portion of the loaded absorbent.

[0068] Additionally or alternatively, during process step S4, the deposited portion of the loaded absorbent is removed by external oscillating excitation of the cleaning element. In this case, the cleaning element is, for example, a vibrating unit located adjacent to the absorption volume 2 of the absorber device 1. The external oscillating excitation loosens the deposited portion of the loaded absorbent within the absorption volume 2, causing it to flake off and be removed from the absorption volume 2. To efficiently transmit the external oscillating excitation through the absorption volume 2, a packing material 6, in particular made of a plastic, is arranged within the absorption volume 2.

[0069] It is also possible that the separated portion of the loaded absorbent is removed by spray nozzles 5. The spray nozzles 5 are not part of the distributor 3. The spray nozzles 5 are arranged on the sides of the absorption volume 2 so that they can be used to remove the separated portion of the loaded absorbent with a cleaning solution supplied by the spray nozzles 5. In this way, the separated portion of the loaded absorbent can be flushed out of the absorption volume 2. It is also possible that the spray nozzles 5 are arranged inside the packing material 6, that is, inside the absorption volume 2.

[0070] Additionally or alternatively, the cleaning element includes self-cleaning surfaces, for example on the packing body 6 in the absorption volume 2. The self-cleaning surface exhibits reduced adhesion for the deposited part of the loaded absorbent, so that the deposited part of the loaded absorbent flakes off when a certain size is reached.

[0071] It is also possible that the cleaning element includes or consists of a grid structure within absorption volume 2. The deposited portion of the loaded absorbent is removed from the grid structure when a predetermined thickness is reached. For example, only a thickness of at least 50 micrometers or at least 100 micrometers of the loaded absorbent can be deposited onto the grid structure before the deposited portion of the loaded absorbent flakes off and is removed from absorption volume 2.

[0072] The methods and / or cleaning elements described above can be combined to increase the efficiency of removing the deposited portion of the loaded absorbent.

[0073] Fig. Figure 2 shows an embodiment of an absorption device 1. The absorption device 1 is designed to absorb carbon dioxide from a gas stream. The absorption device 1 comprises a distributor 3, for example a rotary distributor or a drip distributor, which distributes an absorbent in an absorption volume 2 of the absorption device 1. For a homogeneous distribution of the absorbent in the absorption volume 2, the absorption device 1 can include a distributor layer 4. The distributor layer 4 is arranged between the absorption volume 2 and the distributor 3. The distributor layer 4 is, for example, a trickle screen.

[0074] The distribution layer 4 is designed to provide a uniform film of the absorbent in the absorption volume 2. Additionally or alternatively, the distribution layer 4 is designed such that no deposition of the absorbent and / or the loaded absorbent occurs.

[0075] Within absorption volume 2, the absorbent is brought into contact with the gas stream, thus producing a loaded absorbent. Specifically, the gas stream flows around all components of the absorber device 1. A portion of the loaded absorbent is deposited within absorption volume 2. The absorbent comprises, for example, a metal carbonate that reacts with the carbon dioxide to form a metal bicarbonate. The metal bicarbonate can constitute a large portion of the deposited portion of the loaded absorbent. It is possible that the metal bicarbonate precipitates and / or crystallizes within absorption volume 2.

[0076] The absorption volume 2 consists of an upper absorption layer 21 and a lower absorption layer 22. The upper absorption layer 21 is arranged between the distributor 3 and the lower absorption layer 22. Both the upper absorption layer 21 and the lower absorption layer 22 comprise a packing material 6. The packing material 6 comprises a material selected from the group consisting of ceramics, mineral materials, plastics, and combinations thereof. The packing material 6 may also have a rough surface.

[0077] It is also possible that the lower absorption layer comprises a trickle grid. In particular, the portion of the loaded absorbent is deposited on the packing 6 of the upper absorption layer 21 and / or the lower absorption layer 22. The packing 6 comprises a corrugated or open structure so that falling portions of the deposited loaded absorbent are not blocked by the packing 6.

[0078] The packing material 6 of the upper absorption layer 21 and the packing material 6 of the lower absorption layer differ in their structure such that the specific mass transfer of carbon dioxide into the absorbent is higher in the upper absorption layer 21 than in the lower absorption layer 22. Additionally or alternatively, the inclination angle of the packing material 6 increases from the upper absorption layer 21 to the lower absorption layer 22. It is also possible that the specific surface area of ​​the packing material 6 decreases from the upper absorption layer 21 to the lower absorption layer 22 and / or that the hydrophilicity of the packing material 6 increases from the lower absorption layer 22 to the upper absorption layer 21. In this way, the retention time of the absorbent and / or the loaded absorbent decreases from the upper absorption layer 21 to the lower absorption layer 22.

[0079] The upper absorption layer 21 and the lower absorption layer 22 can be operated with a high supersaturation of the absorbent. It is also possible for the absorbent to be provided as a suspension during operation of the absorber device 1. In particular, the deposition of the loaded absorbent takes place in the lower absorption layer. For example, it is easier to remove the deposited portion of the loaded absorbent from the portion of the absorption volume 2 without significantly impairing the absorption of carbon dioxide into the absorbent.

[0080] The absorber device 1 further comprises a cleaning element designed to remove the deposited part of the loaded absorbent from the absorption volume.

[0081] Distributor 3 is used, for example, as a cleaning element. In this context, distributor 3 is operated at a first flow rate to supply the absorbent to the absorption volume 2. When distributor 3 is operated at a second, higher flow rate, the separated portion of the loaded absorbent can be removed from the absorption volume 2.

[0082] Additionally or alternatively, the cleaning element can include spray nozzles 5. In this case, the spray nozzles 5 are arranged on the sides of the lower absorption layer 22. The spray nozzles 5 can provide a cleaning solution that is used to remove the deposited portion of the loaded absorbent.

[0083] It is also possible that the cleaning element includes a means for removing the deposited portion of the loaded absorbent by oscillating excitation. The means can cause the packing 6 in the upper absorption layer 21 and / or the lower absorption layer 22 to vibrate, so that the deposited portion of the loaded absorbent flakes off and is removed from the absorption volume 2.

[0084] The cleaning element can also include a lattice structure (not shown) configured to release the deposited portion of the loaded absorbent at a predetermined thickness. The predetermined thickness is, for example, at least 50 micrometers or at least 100 micrometers. In particular, the packing 6 of the upper absorption layer 21 and / or the lower absorption layer 22 includes the lattice structure.

[0085] The cleaning element includes, for example, self-cleaning surfaces or consists thereof. In particular, the lower absorption layer 22 comprises the self-cleaning surfaces on its packing body 6. The self-cleaning surface may comprise ethylenetetrafluoroethylene (ETFE). The deposited portion of the loaded absorbent exhibits reduced adhesion to the self-cleaning surfaces. In this way, the deposited portion of the loaded absorbent flakes off spontaneously or can at least be more easily removed by rinsing or vibration.

[0086] The absorber device 1 according to the in Fig. The embodiment shown in 2 can contain all of the cleaning elements described above or only selected ones.

[0087] Fig. Figure 3A shows a specific mass transfer SMT as a function of the height H of the absorption volume 2 of an absorber device 1. In this case, the absorption volume 2 does not comprise an upper and a lower absorption layer that are distinct from each other. The arrow at the top of the curve indicates the flow direction FD of the gas stream through the absorption volume 2. Thus, the gas stream flows from a lower part of the absorption volume 2 to an upper part of the absorption volume 2.

[0088] Out of Fig. 3A shows that the specific mass transfer decreases from the lower part of the absorption volume 2 to the upper part of the absorption volume 2.

[0089] Fig. Figure 3B also shows a specific mass transfer SMT as a function of the height H of the absorption volume 2 of an absorber device 1. The absorber device 1 includes, for example, the one associated with Fig. 2 described structure. The absorption volume 2 therefore consists of an upper absorption layer 21 and a lower absorption layer 22. The flow direction FD is, as in Fig. 3B shown, from the lower absorption layer 22 to the upper absorption layer 21.

[0090] The specific mass transfer (SMT) is increased in the upper absorption layer 21. The specific mass transfer (SMT) is decreased in the lower absorption layer 22. Both effects can be explained by the structure of the upper absorption layer 21 and the lower absorption layer 22. For example, the specific surface area per volume element of the packing material 6 is higher in the upper absorption layer 21 to achieve the desired specific mass transfer trend. Additionally or alternatively, the flow angle of the absorbent from the lower absorption layer 22 to the upper absorption layer 21 is flattened to achieve the desired specific mass transfer trend. In other words, the inclination angle of the packing material 6 in the absorption volume 2 increases from the upper absorption layer 21 to the lower absorption layer 22.

[0091] The features and embodiments described in connection with the figures can be combined with one another according to further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the figures may include alternative or additional features as described in the general section.

[0092] The invention is not limited to the exemplary embodiments described by reference to them. Rather, the invention encompasses every new feature and every combination of features, including in particular every combination of features in the claims and every combination of features in the exemplary embodiments, even if that feature or combination itself is not expressly stated in the claims or exemplary embodiments. Reference symbol list 1 absorber device 2 Absorption volumes 21 upper absorption layer 22 lower absorption layer 3 distributors 4 Distribution layer 5 spray nozzles 6 Filler particles SMT-specific mass transfer FD Flow direction H height

Claims

[1] Method for operating an absorber device (1) for absorbing carbon dioxide from a gas stream, the method comprising the following steps: - Contacting an absorbent with the gas stream within an absorption volume (2), - Production of a loaded absorbent, - Separation of at least a part of the loaded absorbent into the absorption volume (2), - Removal of the separated part of the loaded absorbent from the absorption volume (2) by means of a cleaning element. [2] Method according to claim 1, wherein - the absorbent comprises a metal carbonate, and - the metal carbonate is at least partially converted into a metal hydrogen carbonate during the production of the loaded absorbent. [3] Method according to any of the preceding claims, wherein the absorbent is provided as a suspension. [4] Method according to the preceding claim, wherein - the absorber device (1) comprises a distributor (3), - the distributor (3) is operated with a first flow rate to supply the absorbent within the absorption volume (2), - the distributor (3) is operated with a second flow rate to remove the separated part of the loaded absorbent, and - the second flow rate is higher than the first flow rate. [5] Method according to any of the preceding claims, wherein the removal of the deposited part of the loaded absorbent comprises the removal of the deposited part of the loaded absorbent with a cleaning solution provided by the cleaning element. [6] Method according to any of the preceding claims, wherein the removal of the deposited part of the loaded absorbent comprises the removal of the deposited part of the loaded absorbent by means of an external oscillating excitation provided by the cleaning element. [7] Absorption device (1) for absorbing carbon dioxide from a gas stream, comprising - an absorption volume (2) for an absorbent, and - a cleaning element, wherein - the absorption volume (1) is designed to bring the absorbent into contact with the gas stream, so that a loaded absorbent is produced and a portion of the loaded absorbent is deposited, and - the cleaning element is designed to remove the separated part of the loaded absorbent from the absorption volume (2). [8] Absorption device (1) according to the preceding claim, wherein the cleaning element comprises a distributor (3) configured to distribute the absorbent and / or a cleaning solution in the absorption volume (2). [9] Absorber device (1) according to the preceding claim, further comprising a distribution layer (4). [10] Absorber device (1) according to one of the preceding claims, wherein the cleaning element comprises self-cleaning surfaces. [11] Absorber device (1) according to one of the preceding claims, wherein the cleaning element comprises a grid structure, the grid structure being configured to release the deposited portion of the loaded absorbent at a predetermined thickness of the deposited portion of the loaded absorbent. [12] Absorber device (1) according to one of the preceding claims, wherein the cleaning element comprises spray nozzles (5). [13] Absorber device according to one of the preceding claims, wherein the cleaning element is configured to remove the deposited part of the loaded absorbent from the absorption volume (2) by means of external oscillating excitation. [14] Absorber device (1) according to one of the preceding claims, wherein the absorption volume (2) comprises an upper absorption layer (21) and a lower absorption layer (22). [15] Absorber device (1) according to one of the preceding claims, wherein the upper absorption layer (21) comprises a filler (6), in particular comprising or consisting of a plastic. [16] Absorber device (1) according to the preceding claim, wherein the packing body (6) comprises a wave structure or an open structure. [17] Absorber device (1) according to one of claims 14 to 16, wherein in operation of the absorber device (1) a specific mass transfer in the upper absorption layer (21) is higher than in the lower absorption layer (22). [18] Absorber device (1) according to one of claims 14 to 17, wherein in operation of the absorber device (1) a deposition rate of the loaded absorbent in the lower absorption layer (22) is higher than in the upper absorption layer (21). [19] Absorber device according to one of claims 14 to 18, wherein an inclination angle in a packing body (6) in the absorption volume (2) increases from the upper absorption layer (21) to the lower absorption layer (22). [20] Absorption device according to one of claims 14 to 19, wherein a specific surface area of ​​a packing body (6) in the absorption volume (2) decreases from the upper absorption layer (21) to the lower absorption layer (22).

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