Direct air capture process

Abstract

Described is a device for recovering carbon dioxide from a gaseous medium, comprising at least one preconditioning unit, at least one drying unit, and at least one CO2 unit. Also described are a process for recovering carbon dioxide from a gaseous medium as well as the use of the device and of the process.

Description

[0001] Description

[0002] Direct Air Capture Process

[0003] The invention relates to a device for obtaining carbon dioxide from a gaseous medium, a method for obtaining carbon dioxide from a gaseous medium, and the use of the device and the method for obtaining carbon dioxide.

[0004] Carbon dioxide emissions into the atmosphere are currently considered a major driver of climate change. Carbon capture and storage (CCS) technologies are efficient and effective methods for reducing carbon dioxide emissions into the atmosphere.

[0005] Known methods for capturing carbon dioxide include absorption, adsorption, membrane-based systems, electrochemical separation and cryogenic separation.

[0006] WG2016 / 005226A1, WO2015 / 185434A1, and WG2014 / 170184A1 describe exemplary processes for the recovery of carbon dioxide using a chemisorbent following a temperature-vacuum cycling process. Amine-based chemisorbents are often prone to aging and degradation when the material comes into contact with oxygen at temperatures above approximately 60°C. This can occur during the desorption phase at temperatures around 100°C if countermeasures are not taken, such as creating an inert atmosphere in the system using steam or other gases. These protective measures are complex and expensive. During desorption, steam is introduced to displace the residual oxygen, thus preventing damage to the material through degradation.Before the system returns to the adsorption phase (i.e., the absorption of CO2) after the desorption phase, by bringing the sorbent material into contact with air, it is cooled to approximately 50 °C. This represents an additional process step, which can reduce the system's time and energy efficiency.

[0007] WO2022 / 109746A1 describes a process for extracting carbon dioxide using physisorbents in polar (cold, dry) regions, as these materials preferentially absorb water from the ambient air. When using physisorbents, there is an approach to limiting the application of such a system to polar regions of the Earth, because the air there contains less water due to the low temperatures compared to temperate, subtropical, or tropical climates. However, technical pre-drying cannot be completely dispensed with, as it cannot be guaranteed that a dew point temperature of, for example, -40 °C or -60 °C will be maintained consistently throughout the year. Furthermore, the effort required to install and operate a system in polar regions is enormous compared to developed regions of the Earth.

[0008] Knox et al., Investigation of Desiccants and CO2 Sorbents for Exploration Systems 2016-2017, ICES-2017-188, disclose the use of physisorbents to separate CO2 from the cabin air of spacecraft and space stations. This approach uses a so-called four-bed molecular sieve approach, which involves interconnecting modules for pre-drying the cabin air and for CCH separation.

[0009] EP1142623A2 discloses a temperature-vacuum cycling process for isolating carbon dioxide from a moist hot gas mixture.

[0010] US2010251887A1 describes a process for isolating carbon dioxide from a gas mixture comprising a temperature swing adsorption step.

[0011] WO2014 / 012966A1 discloses a device for an adsorption-desorption alternating reaction.

[0012] The object of the present invention is to provide a device for obtaining carbon dioxide from a gaseous medium, as well as a method for obtaining carbon dioxide from a gaseous medium, which at least partially overcomes the above-mentioned disadvantages.

[0013] This object is achieved by the device according to the invention according to claim 1 and the method according to the invention according to claim 10.

[0014] Further advantageous embodiments of the invention emerge from the dependent claims and the following description of preferred embodiments of the present invention. A device according to the invention for obtaining carbon dioxide from a gaseous

[0015] Medium includes:

[0016] - at least one preconditioning unit,

[0017] - at least one drying unit and

[0018] - at least one CCh unit.

[0019] The gaseous medium can be the atmosphere, ambient air, exhaust gases, e.g., from industrial plants, gas mixtures, point sources, etc. The gaseous medium includes, among other things, carbon dioxide.

[0020] A device according to the invention has at least one preconditioning unit. A preconditioning unit is a component by means of which the gaseous medium can be supplied in a suitable form to the further component(s). A preconditioning unit can, for example, cool or heat the gaseous medium to a defined temperature. A preconditioning unit can compress or expand the gaseous medium using pressure in addition to, or alternatively to, adjusting the temperature.

[0021] A preconditioning unit can also be a line, such as a bypass line, through which the gaseous medium can be supplied to the other component(s). A line such as a bypass line can be used as a preconditioning unit, especially if the gaseous medium is already present in a suitable form.

[0022] By using the preconditioning unit, a device according to the invention can also be used for different climatic conditions (e.g. higher FhO contents in the ambient air at higher temperature and / or air humidity).

[0023] A device according to the invention further comprises at least one drying unit. In the drying unit, the gaseous medium, in particular the preconditioned gaseous medium, can be dried to a specific moisture content.

[0024] The drying unit preferably has at least one suitable material by means of which the moisture content can be adjusted. The material can be distributed homogeneously within the drying unit. Alternatively, the material can also be distributed in layers within the drying unit. In particular, with a layered structure of the drying unit, the drying unit can have a drying gradient. A first layer can therefore lead to an initial drying down to a certain moisture content. In the further layer of the drying unit, further drying down to a certain moisture content can take place. A drying unit can have any number of layers. Ideally, the layers are coordinated with one another.

[0025] A certain amount of carbon dioxide can also be adsorbed in the drying unit. For this purpose, the drying unit can contain at least one material that can adsorb carbon dioxide.

[0026] The drying unit preferably adsorbs 99.0% (corresponds to dew point -40 °C after drying unit), more preferably -99.7% (dew point -50 °C), even more preferably 99.9% (dew point -60 °C) of the amount of H2O present in the gaseous medium.

[0027] A device according to the invention further comprises at least one CCH unit. A CO2 unit can adsorb a certain amount of carbon dioxide. The CCH unit preferably comprises at least one material that can adsorb carbon dioxide.

[0028] The CC>2 unit preferably adsorbs 80%, more preferably 90%, even more preferably 99% of the amount of carbon dioxide present in the gaseous medium.

[0029] In one embodiment, the preconditioning unit conditions the gaseous medium to a dew point of < 10 °C, preferably to a dew point of < 5 °C. A dew point is the condensation point of water in air. The preconditioning unit can cool or heat the gaseous medium and adjust it to a defined pressure so that the gaseous medium reaches the desired dew point.

[0030] In a further embodiment, the CCh unit comprises at least one adsorption unit and at least one desorption unit. The CC>2 unit can also have a unit that can serve alternately as an adsorption unit and a desorption unit. Depending on the process stage, the CCh unit can preferably adsorb CO2 or desorb CO2 and be configured accordingly.

[0031] In a further embodiment, the drying unit comprises at least one adsorption unit and at least one desorption unit. The drying unit can also have a unit that can serve alternately as an adsorption unit and a desorption unit. Depending on the process stage, the drying unit can preferably adsorb CO2 or desorb CO2 and be designed accordingly. The drying unit can be designed independently of the CCh unit.

[0032] A device according to the invention can further comprise at least one intercooler. Preferably, an intercooler is arranged downstream of the drying unit. An intercooler can also be arranged upstream of the CCh unit. In one embodiment, an intercooler is arranged between the drying unit and the CCh unit.

[0033] An intercooler preferably cools the incoming gaseous medium to a defined temperature. The temperature is preferably <15 °C, more preferably <10 °C, and even more preferably <6 °C. The incoming gaseous medium is particularly preferably cooled to a temperature of 5 °C.

[0034] With additional and / or larger air conditioning units, cooling could be achieved even further after the drying unit (e.g. to -20 °C to -40 °C).

[0035] In one embodiment, a device according to the invention comprises at least one heat exchanger unit. The heat exchanger unit can be used, in particular, for heat recovery. By using a heat exchanger unit, the energy required by external energy sources can be reduced, thus increasing the energy efficiency of the device.

[0036] The heat recovered by the heat exchanger unit can be used, for example, for the desorption of H2O from the drying unit and / or carbon dioxide from the CCh unit.

[0037] The energy requirement of the device according to the invention can be further reduced by using at least one heat pump. The heat pump can generate the energy for desorption in the drying unit and / or the CCh unit. The cold exhaust air from the heat pump can be used for cooling, e.g., in the preconditioning unit and / or the intercooler.

[0038] A device according to the invention can further comprise at least one blower device. The blower can serve to guide the gaseous medium through the device. The blower can be arranged on the inlet side and / or the outlet side of the device. If the blower is arranged on the inlet side, the gaseous medium is forced into the device (for example, into the preconditioning unit). If the blower is arranged on the outlet side of the device, the suction created by the blower draws the gaseous medium through the device.

[0039] There may be multiple blower units or just one. For the simplest possible design, you can try to avoid multiple blowers and adjust the airflow distribution using variable throttles, as long as the resulting additional pressure loss is acceptable.

[0040] The at least one drying unit and / or the at least one CO2 unit can comprise at least one physisorbent. A physisorbent is a compound that can bind a substance (e.g., a gas such as carbon dioxide) to itself through physical forces. Ideally, a physisorbent desorbs the adsorbed substance under controlled conditions. This can be achieved, for example, by applying heat, pressure, the addition of other substances with the release of the first adsorbed substance, etc.

[0041] The physisorbents used are preferably robust, age-resistant, and commercially available on a large scale. Compared to chemisorbents, there are generally no signs of aging or degradation within the temperature range used.

[0042] The physisorbent can be a homogeneous substance or a mixture. Preferably, the at least one physisorbent is a solid. The at least one physisorbent can be selected from the group consisting of silica gel, zeolite, aluminosilicate, and MOF (metal organic framework).

[0043] The drying unit preferably has a layered structure of physisorbents. In one embodiment, the drying unit has at least one layer of silica gel and at least one layer of zeolite. The at least one layer of silica gel is preferably arranged in the inlet area of ​​the drying unit so that the silica gel can perform an initial drying process. The thus pre-dried medium is then passed through the at least one zeolite layer so that further drying of the pre-dried medium can take place.

[0044] In an alternative embodiment of the drying unit, it comprises at least one layer of silica gel and at least two layers of zeolite. A layer of zeolite, a so-called protective layer, can be arranged in the inlet area of ​​the drying unit. The protective layer can serve to remove impurities from the gaseous medium, thus protecting the subsequent layers. At least one layer of silica gel can be arranged on the protective layer so that the silica gel can carry out an initial drying process. The thus pre-dried medium is then passed through the at least one zeolite layer, so that further drying of the pre-dried medium can take place.

[0045] The ratio of the first layer (e.g. silica gel) and the second layer (e.g. zeolite) may be in the range between 1.5 and 3.5, preferably in the range between 2.0 and 3.0, more preferably in the range between 2.3 and 2.5.

[0046] A device according to the invention can be operated at a CO2 partial pressure in the range of approximately 380 to 480 ppm, preferably in the range of 400 to 450 ppm, and particularly preferably 420 ppm. This results in a different ratio of CO2 and FW partial pressure. For applications under atmospheric conditions, an optimal design of the bed heights of the adsorption units can be advantageous.

[0047] Preferably, the drying is carried out such that the medium leaving the drying unit has a moisture content of 0.0196% to 0.007% (dew point -40 °C), preferably of 0.007% to 0.0022% (dew point -50 °C), more preferably of 0.0022% to 0.0006% (dew point -60 °C).

[0048] The CCh unit can also have a layered or homogeneous structure of physisorbent(s). Preferably, the CCh unit has a homogeneous structure of physisorbent(s). The physisorbent can be zeolite. The physisorbents can also be a mixture of at least two different zeolites.

[0049] The bed heights or layer thicknesses in the drying unit and the CCh unit can also have a specific ratio. The ratio can be in the range of 1.2 to 2.5, preferably in the range of 1.5 to 2.0, and more preferably in the range of 1.7 to 1.9. The ratio of the bed heights or layer thicknesses in the drying unit and the CCh unit is particularly preferably 1.8.

[0050] Furthermore, the present invention relates to a process for obtaining carbon dioxide comprising the steps of: - drying a gaseous medium,

[0051] - Adsorbing CO2 from the gaseous medium in a CCh unit, and

[0052] - simultaneous recovery of CO2 by desorbing CO2 in a CCh unit.

[0053] Preferably, a method according to the invention is carried out in a device according to the invention. The features of the device should also be applicable to the method.

[0054] The gaseous medium can be the atmosphere, ambient air, exhaust gases, e.g., from industrial plants, gas mixtures, point sources, etc. The gaseous medium includes, among other things, carbon dioxide.

[0055] A method according to the invention comprises the step of drying a gaseous medium. The drying can be carried out in at least one drying unit. The gaseous medium, in particular the preconditioned gaseous medium, can be dried to a specific moisture content.

[0056] Drying can be achieved using at least one suitable material by means of which the moisture content can be adjusted. The material can be present as a homogeneous material. Alternatively, the material can also be present in layers. In particular, when present in layers, a drying gradient can exist. A first layer can therefore lead to an initial drying down to a certain moisture content. In the subsequent layer, further drying down to a certain moisture content can take place. Any number of layers can be present. Ideally, the layers are coordinated with one another. The layer(s) can be at least one physisorbent, as described herein.

[0057] During drying, preferably 99.0%, more preferably 99.7%, even more preferably 99.9% of the amount of H2O present in the gaseous medium can be adsorbed.

[0058] Preferably, the gaseous medium is conditioned before drying. Conditioning is used, in particular, to supply the gaseous medium to the process at an appropriate temperature and / or pressure.

[0059] Conditioning can also be understood as the targeted supply of the gaseous medium via a line. In one embodiment, a method according to the invention comprises cooling the gaseous medium before adsorbing the CO2. The cooling of the gaseous medium can be achieved by an intercooler. Alternatively, other components for controlling the temperature of the gaseous medium are also conceivable. For example, this could be an air-water heat exchanger.

[0060] The incoming gaseous medium is preferably cooled to a defined temperature. The temperature is preferably <15 °C, more preferably <10 °C, and even more preferably <6 °C. The incoming gaseous medium is preferably cooled to a temperature of 5 °C.

[0061] A method according to the invention may further comprise the step of heat recovery, in particular the step of heat recovery by means of a heat exchanger unit. Heat recovery can reduce the energy consumption of a method according to the invention compared to prior art methods, thereby increasing energy efficiency.

[0062] The heat recovered from heat recovery can be used, for example, for the desorption of carbon dioxide from the drying unit and / or the CCh unit.

[0063] The energy requirement of the device according to the invention can be further reduced by using at least one heat pump. The heat pump can generate the energy for desorption in the drying unit and / or the CCh unit. The cold exhaust air from the heat pump can be used for cooling, e.g., in the preconditioning unit and / or the intercooler.

[0064] In one embodiment, a method according to the invention comprises the step of transporting the gaseous medium by means of a blower. The blower can correspond to the blower of a device according to the invention.

[0065] The blower can be used to guide the gaseous medium through the device. The blower can be located on the inlet and / or outlet side of the device. If the blower is located on the inlet side, the gaseous medium is forced into the device (e.g., into the preconditioning unit). If the blower is located on the outlet side of the device, the suction created by the blower draws the gaseous medium through the device.

[0066] In a process according to the invention, the adsorbed CO2 is preferably desorbed by heating and under vacuum. The unit in which the CO2 is adsorbed is heated to a defined temperature. This heating releases the CO2 from the unit and allows it to be removed, preferably with high purity.

[0067] In a process according to the invention, H2O is preferably adsorbed simultaneously in one drying unit, while H2O is desorbed in another drying unit. When CO2 is desorbed in one CO2 unit, CO2 is preferably adsorbed simultaneously in the other CCh unit. It is always adsorbed in one drying unit and CCh unit and desorbed simultaneously in the other drying unit and CCh unit.

[0068] The CO2 can preferably be removed from the device or method at a purity of >80%, more preferably at a purity of >90%, even more preferably at a purity of >95%. In some embodiments, the CO2 is removed at a purity of >99%.

[0069] The adsorbed CO2 can be desorbed by heating to a temperature of >50°C, in particular >80°C, preferably >100°C, more preferably >120°C, and even more preferably >140°C. Preferably, in a process according to the invention, no steam is required for the desorption of the CO2. Preferably, the desorption of the CO2 takes place under vacuum at a pressure of 10 mbar absolute.

[0070] Furthermore, the present invention relates to the use of a device according to the invention or a method according to the invention for obtaining carbon dioxide from a gaseous medium.

[0071] The resulting carbon dioxide can be used as a starting material for other compounds. For example, the carbon dioxide can be used as a starting material for the production of plastics, e-fuels, etc.

[0072] Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 schematically shows an embodiment of a device according to the invention, Fig. 2 schematically shows an embodiment of a device according to the invention, Fig. 3 schematically shows an embodiment of a drying unit according to the invention and a CCh unit,

[0073] Fig. 4 schematically shows the time sequence of a method according to the invention, Fig. 5 schematically shows an embodiment of a device according to the invention, Fig. 6 schematically shows an embodiment of a device according to the invention, Fig. 7 schematically shows an embodiment of a device according to the invention, Fig. 8 schematically shows an embodiment of a device according to the invention, and Fig. 9 schematically shows an embodiment of a drying unit according to the invention and a CCh unit.

[0074] An embodiment of a device 100 according to the invention is shown in Fig. 1. The embodiment shown comprises a preconditioning unit 101, a drying unit 102, an intercooler 103, a CCh unit 104, a heat exchanger unit for heat recovery 105, and a suction-type fan 106. Suitable physisorbents can be present in the drying unit and / or the CCh unit.

[0075] Fig. 2 shows an embodiment of a device 200 according to the invention. Device 200 includes two drying units 202A and 202B and two CCh units 204A and 204B, each for adsorption and desorption. These units are arranged in parallel and can alternate between the respective operating states. This system can be referred to as a "forced-coupled system" because the process steps in the drying units 202A, 202B and CCh units 204A, 204B are coordinated with one another in such a way that they can be operated alternately without interruption. When the lower drying unit 202A is in adsorption, the lower CCh unit 204B is in desorption. When the upper drying unit 202B is in desorption, the upper CCh unit 204A is in adsorption. In the preconditioning unit 201, the sucked-in moist supply air 208 is cooled down to 5 °C if the ambient temperature is greater than 5 °C.Depending on the humidity of the ambient air, condensation occurs down to the dew point of 5°C, so that a portion of the water is separated from the air in the preconditioning unit 201. This requires less energy than if it occurs in the subsequent drying unit 202A, where air drying is based on adsorption (the condensation enthalpy is lower than the adsorption enthalpy of H2O on physisorbents). By cooling the incoming air to 5°C, a favorable adsorption capacity of the subsequent drying unit 202A is further achieved. At an ambient temperature below 5°C, the air passes through the preconditioning unit 201 without cooling (the cooler is not active) or via a bypass. In the drying unit 202A, the water is separated from the intake air by means of adsorption A. For this purpose, the drying unit 202A is divided, for example, into two stages.In the first stage, coarse drying takes place using silica gel. In the second stage, fine drying takes place using a zeolite (preferably a 13X-type zeolite) to a residual moisture content corresponding to a dew point of -60 to -40 °C. The drying stage is ideally designed such that a bed height of preferably 171 mm (85 to 340 mm also possible) is selected for the silica gel and a bed height of 71 mm (35 to 140 mm also possible) for the zeolite (see also Fig. 3). The drying phase of a drying unit 202A is operated up to a maximum water breakthrough of 1000 ppm (dew point approx. -22.5 °C). The same applies to the drying unit 202B. During adsorption, adsorption heat is released (exothermic process). As a result, the dry air leaves the drying unit 202A at a temperature approximately 15 to 30 K higher than the inlet temperature.In order to achieve the best possible adsorption capacity in the downstream CCh unit 204A, the dried air is passed through an intercooler 203 and cooled back to 5 °C. The dry and cooled air is then passed through a CCh unit 204A, in which the CO2 is separated from the air by means of adsorption A on a zeolite (preferably a 13X type zeolite). The CC>2 stage is ideally designed in such a way that it has a bed height of preferably 135 mm (67 to 270 mm also possible) (see also Fig. 3). This maintains a bed height ratio of 1.8 for the drying units 202A and 202B and the CCh units 204A and 204B. This represents an ideal configuration for the partial pressure ratio of H2O and CO2 in the intake air.

[0076] Ambient air represents the maximum humidity of the air when the humidity content of the air corresponds to the dew point of 5 °C after the preconditioning unit 201 and the air has a CCh concentration of 420 ppm (380 to 480 ppm also possible). The CCh adsorption process is carried out up to a CO2 breakthrough of preferably 140 to 160 ppm in order to ensure the most efficient use of the pre-dried air. Operation of the CCh adsorption is still reasonably possible up to a CCh breakthrough of 360 ppm (at a concentration of 420 ppm in the ambient air) in order to increase the CCh yield per adsorption phase, although this results in an energetic disadvantage, since disproportionately more effort is invested in air drying than CO2 can be separated from the adsorption phase. The dry air is used downstream of the CCh unit 204B for desorption (regeneration) B of the drying stage.For this purpose, a portion of the air (volume flow rate of preferably 5%, in the range of 1 to 20%) is passed through a heat recovery heat exchanger 205, which in turn is fed by the warm, moist exhaust air from the regenerating drying stage. The desorption volume flow diverted from the main volume flow can be adjusted using a variable throttle. The dry desorption air, thus preheated, is passed in countercurrent through the drying unit 202B. The drying units 202A and 202B also have an internal heat exchanger to heat the sorbent material (silica gel and zeolite) to preferably 150°C (120 to 200°C is also possible); desorbing can also occur at a higher or lower temperature. A lower temperature extends the desorption phase and / or requires a higher air volume flow. A higher desorption temperature can shorten the desorption time.) The air leaves the drying unit 202B at a temperature between 80 and 150 °C (depending on the water desorption phase). The warm, moist exhaust air is passed through an air-to-air heat exchanger, which preheats the dry desorption air. Desorption in the drying unit 202B is terminated when the H2O concentration at the outlet falls below 1500 ppm (at 5% volume flow). After H2O desorption is complete, the internal heat exchanger is switched off, and the sorbent material is further cooled with dry, no longer preheated air, preferably to at least 60 °C, in order to provide sufficient adsorption capacity from the start in the subsequent adsorption and thus prevent unwanted water breakthrough. A volume flow rate of 5 to 20% is advantageously used for cooling.At the system outlet, a fan 206 is mounted, which draws air through the system and expels exhaust air 207 from the system. For a good compromise between pressure loss across the adsorption units and CO2 yield, an average flow velocity of 0.2 m / s across the adsorber units' end faces is favorable (0.1 to 0.4 m / s is also possible) (see also Fig. 3). The dry air used for desorption B in the CO2 unit is tapped after the heat exchanger unit for heat recovery 205. For the second desorption phase, the volume flow rate via the heat exchanger for heat recovery 205 is adjusted so that dry and preheated air is available for desorption in the CO2 and drying stages. Before the vacuum pump 210, the desorbed and gaseous water is condensed on a condenser 209 (outlet temperature 5 °C), so that the compressor work of the vacuum pump 210 is reduced.After desorption B of the CO2 unit 204B is completed, the unit remains sealed. The heat stored in the sorbent remains in the system until the next adsorption is started. As the just-desorbed CO2 unit begins adsorption, the heat stored in the CO2 sorbent is conducted by the air flow to the next drying stage to be desorbed. The residual air 211 and the CO2 product stream 212 with a purity of >99% are removed from the device. During adsorption A on one side of the CO2 unit 204A, desorption B takes place on the other side of the CO2 unit 204B (Fig. 2: labeled adsorber "A" in adsorption; "B" in desorption; Fig. 4 shows an example program sequence). For this purpose, the CO2 unit 204B to be desorbed is sealed and evacuated to an absolute pressure of preferably 10 mbar absolute. This removes most of the residual air from the system.The sorbent material is then heated to preferably 150 °C (120 to 200 °C also possible) using an internal heat exchanger. The CO2 is desorbed and continuously removed by vacuum pump 210. If the purity is sufficient (> 95%, preferably > 99%), the desorbed CO2 is fed into the product path. Since it cannot be prevented during the adsorption phase that a very small amount of residual moisture can penetrate into the CC>2 unit 204A (due to a slight water breakthrough after the drying unit 202A), the CCh desorption is followed by F desorption in the CC>2 unit 204B under vacuum to remove the residual H2O load.For this purpose, while maintaining the desorption temperature of preferably 150 °C (also possible up to 200 °C), a dry purge air with a volume flow rate of 10% (also possible 1 to 20%) is introduced, which is continuously extracted by the vacuum pump 210, maintaining a pressure of preferably 100 mbar absolute (also possible 10 to 800 mbar) ("2-stage desorption"). The dry air used for desorption is tapped downstream of the heat exchanger for heat recovery 205. For the second phase of desorption, the volume flow rate is adjusted via the heat exchanger for heat recovery 205 so that dry and preheated air is available for desorption in the CCh unit 204B and the drying unit 202. Before the vacuum pump 210, the desorbed and gaseous water is condensed on a condenser 209 (outlet temperature 5 °C), so that the compressor work of the vacuum pump 210 is reduced.After desorption B of the CCh unit 204B is completed, the unit remains closed. The heat stored in the sorbent remains in the system until the next adsorption is started. When the just-desorbed CCh unit 204A begins adsorption, the heat stored in the CCh sorbent is conducted by the air flow to the next drying unit 202B to be desorbed. In a further embodiment, the intermediate cooling in the intercooler 203 between the drying units 202A and 202B and the CCh units 204A and 204B is used to cool the air to below 5°C, preferably to -20°C to -40°C (always above the dew point temperature of the dried air after the drying units 202A and 202B), in order to increase the CCh adsorption capacity of the subsequent CCh unit 204A. Fig.3 shows a schematic structure of a drying unit 302 and a CCh unit 304. The drying unit 302 has a layered structure.Two layers are shown here by way of example. A first layer can be silica gel. The first layer can have a thickness (or filling height) of approximately 171 mm. A second layer, adjacent to the first layer, can be zeolite (e.g., 13X type). The second layer can have a thickness (or filling height) of approximately 71 mm. The CCh unit 304 can, for example, have one layer. One layer can be a zeolite layer (e.g., 13X type zeolite). The layer can have a thickness (or filling height) of 135 mm. The drying unit 302 and the CCh unit 304 each have an inflow surface 313. For a good compromise between pressure drop across drying unit 302 and CCh unit 304 and CCh yield, an average face velocity of 0.2 m / s is favorable (0.1 to 0.4 m / s is also possible). Depending on the process stage, drying unit 302 and CCh unit 304 can be in adsorption or desorption mode.

[0077] Fig. 4 shows an embodiment of a time course of a method according to the invention. While the drying unit A and the CCh unit A are in the state of adsorbing CCh, the drying unit B and the CCh unit B are in the state of desorbing CCh. In this embodiment, the drying unit and the CCh unit each have two units A and B. In the drying unit A, the adsorption of H2O stops if an FO concentration of > 1000 ppm can be detected at the end of the unit. In the CCh unit A, the adsorption of CO2 stops if a CCh concentration of > 140 ppm can be detected at the end of the unit.

[0078] Simultaneously, parallel processes are running in drying unit B and CCh unit B. Drying unit B and CCh unit B are in the desorption phase. Drying unit B is heated and purged with purge air to allow the H2O to desorb. The drying unit is then cooled to room temperature and waits for the next reaction step. During the process flow in drying unit B, the CCh unit is first evacuated, heated to desorb CO2, and purged under vacuum to allow the H2O to be desorbed. The unit then waits for the next reaction step while maintaining the heat.

[0079] After adsorption, drying unit A and CCh unit A switch to the desorption state. Drying unit A is heated and purged so that the adsorbed H2O can desorb again. It then cools and waits until the next adsorption. In the meantime, the CCh unit is evacuated, heated for CCh desorption, and purged under vacuum for H2O desorption. The unit waits while maintaining the heat until the next adsorption. Drying unit B and CCh unit B are in adsorption during this time. In drying unit B, H2O is adsorbed until a W concentration of > 1000 ppm is reached at the end of the drying unit. In CO2 unit B, the adsorption of CO2 stops if a CC>2 concentration of > 140 ppm can be detected at the end of the unit. Afterwards, another change occurs and the drying unit A and the CCh unit A return to the adsorption state.The drying unit B and the CCh unit B return to the desorption state.

[0080] In a further embodiment of the device 500, shown in Fig. 5, the volume flow used for desorption of the drying unit 502B is decoupled from the system's main fan 515 by using a separate, controllable fan 506. This allows the volume flow portion of the desorption fan 514 to be variably controlled or regulated over time during desorption and guided along the moisture content of the exiting moist exhaust air. This allows the amount of air used for desorption in the drying stage to be reduced. The preconditioning unit 501, the drying unit 502A, the intercooler 503, the CCh unit 504A and 504B, the heat exchanger unit for heat recovery 505, the exhaust air 507, the moist supply air 508, the condenser 509, the vacuum pump 510, and the residual air 511 can correspond to those shown in Fig. 2. The CCh product stream 512 can have a purity of > 99%. Adsorption in the drying unit orof the CCh unit is marked by A, desorption by B.

[0081] In a further embodiment of the device 600 according to Fig. 6, the air to be conveyed through the system is not sucked in, but rather forced by a fan 606 arranged upstream of the system. Thus, in the event of a leak in the system downstream of the drying unit 602A and 602B, the air would escape at the leak, instead of (moist, non-pre-dried) ambient air being sucked in through the leak and passed through the CO2 unit 604A and 604B, thus reducing the CO2 adsorption capacity due to the competitive adsorption of H2O and CO2 in sorbents (e.g., zeolites). The preconditioning unit 601, the intercooler 603, the heat exchanger unit for heat recovery 605, the exhaust air 607, the moist supply air 608, the condenser 609, the vacuum pump 610, and the residual air 611 can correspond to those shown in Fig. 2 and Fig. 5, respectively. The CO2 product stream 612 can have a purity of > 99%. Adsorption in the drying unit 602A and 602B, respectively.The CO2 unit 604A and 604B is marked by A, desorption by B.

[0082] In a further embodiment of the device 700 according to Fig. 7, energy is recovered from the moist, warm exhaust air 707 after the drying unit 702A and from the CO2-residual air mixture exiting the CO2 unit 704B by means of a heat pump. The energy can in turn be used to heat the sorbent materials using the internal heat exchangers in the CCh unit 704B and the drying unit 702B. The preconditioning unit 701, the intercooler 703, the heat exchanger unit for heat recovery 705, the fan 706, the moist supply air 708, the vacuum pump 710, and the residual air 711 can correspond to those shown in Fig. 2, Fig. 5, and Fig. 6, respectively. The CCh product stream 712 can have a purity of > 99%. Adsorption in the drying unit 202A and 202B or the CCh unit 204A and 204B is indicated by A, desorption by B.

[0083] In a further embodiment of the device 800 according to Fig. 8, the energy from the cooling of the sucked-in ambient air and the intermediate cooling by means of an intercooler 803 after the drying unit 802A and 802B is raised to a high temperature level by means of a heat pump, so that the energy can be used to heat the internal heat exchangers of the adsorption units (at least in a supporting capacity) of the drying unit 802A and 802B and the CCh unit 804A and 804B. The preconditioning unit 801, the heat exchanger unit for heat recovery 805, the fan 806, the exhaust air 807, the moist supply air 808, the condenser 809, the vacuum pump 810, and the residual air 811 can correspond to those of Fig. 2, Fig. 5, Fig. 6, and Fig. 7, respectively. The CO2 product stream 812 can have a purity of > 99%. Adsorption in the drying unit 802A and 802B or the CO2 unit 804A and 804B is indicated by A, and desorption by B. In Fig.8, the condenser side of the heat pump circuit is shown only for adsorbers in desorption.

[0084] Fig. 9 shows a schematic structure of a drying unit 902 and a CO2 unit 904. The drying unit 902 has a layered structure. Three layers are shown here as an example. A first layer can be zeolite (e.g., type 13X), a so-called protective layer, a second layer (e.g., silica gel), and a third layer can be zeolite (e.g., type 13X), a so-called barrier layer. A bed of zeolite (preferably type 13X) with a bed height of 20 to 70 mm, preferably 30 mm, can be placed in front of the silica gel. The total bed height of 242 mm, considered ideal, is maintained. The remaining bed height for the second layer (e.g., silica gel) and the third layer (e.g., type 13X zeolite (barrier layer)) is divided accordingly in the same ratio of 171 mm to 71 mm. This results in a filling height of 150 mm for the second layer (e.g. silica gel) and 62 mm for the barrier layer (e.g. zeolite type 13X).The upstream first layer (e.g., a zeolite bed) absorbs the finest water droplets or aerosols from the drawn-in air when conditions are very close to the dew point. This layer can protect the second layer (e.g., the silica gel) from excessive and rapid water absorption during adsorption, which could cause the second layer (e.g., the silica gel) to burst and be destroyed. This can extend the service life of the sorbent materials, such as the physisorbents, in the drying stage. The CCh unit 904 can have one layer. The layer can be zeolite (e.g., zeolite 13X type). The layer can have a thickness of 135 mm.

[0085] The drying unit 902 and the CC>2 unit 904 each have an inflow surface 913.

[0086] For a good compromise between pressure loss across drying unit 902 and CO2 unit 904 and CCh yield, an average flow velocity of 0.2 m / s at the end faces is favorable (0.1 to 0.4 m / s is also possible). Depending on the process stage, drying unit 902 and CCh unit 904 can be in adsorption or desorption mode.

[0087] List of reference symbols , 200, 500, 600, 700, 800 Device , 201 , 501 , 601 , 701, 801 Preconditioning unit , 202A, 202B, 302, 502A, 502B, A, 602B, 702A, 702B, A, 802 B, 902 Drying unit , 203, 503, 603, 703, 803 Intercooler , 204A, 204B, 304, 504A, 504B, A, 604B, 704A, 704B, A, 804B, 904 CCh unit , 205, 505, 605, 705, 805 Heat exchanger unit for heat recovery, 206, 506, 606, 706, 806 Fan, 507, 607, 707, 807 Exhaust air, 508, 608, 708, 808 Humid supply air, 509, 609, 809 Condenser, 510, 610, 710, 810 Vacuum pump, 511, 611, 711, 811 Residual air, 512, 612, 712, 812 CCh product stream, 913 Inflow area

[0088] Desorption blower

[0089] Main fan

Claims

Patent claims 1. Device (100, 200, 500, 600, 700, 800) for obtaining carbon dioxide from a gaseous medium, comprising: - at least one preconditioning unit (101, 201, 501, 601, 701, 801), - at least one drying unit (102, 202A, 202B, 302, 502A, 502B, 602A, 602B, 702A, 702B, 802A, 802B, 902) and - at least one CCh unit (104, 204A, 204B, 304, 504A, 504B, 604A, 604B, 704A, 704B, 804A, 804B, 904).

2. Device according to claim 1, wherein the preconditioning unit (101, 201, 501, 601, 701, 801) conditions the gaseous medium to a dew point < 10°C, preferably to a dew point < 5°C.

3. Device according to claim 1 or 2, wherein the CCh unit (104, 204A, 204B, 304, 504A, 504B, 604A, 604B, 704A, 704B, 804A, 804B, 904) comprises at least one adsorption unit and at least one desorption unit.

4. Device according to at least one of claims 1 to 3, wherein the drying unit (102, 202A, 202B, 302, 502A, 502B, 602A, 602B, 702A, 702B, 802A, 802B, 902) comprises at least one adsorption unit and at least one desorption unit.

5. Device according to at least one of claims 1 to 4, further comprising at least one intercooler (103, 203, 503, 603, 703, 803).

6. Device according to at least one of claims 1 to 5, further comprising at least one heat exchanger unit (105, 205, 505, 605, 705, 805).

7. Device according to at least one of claims 1 to 6, further comprising at least one blower device (106, 206, 506, 606, 706, 806).

8. Device according to at least one of claims 1 to 7, wherein the at least one drying unit (102, 202A, 202B, 302, 502A, 502B, 602A, 602B, 702A, 702B, 802A, 802B, 902) and / or the at least one CO2 unit (104, 204A, 204B, 304, 504A, 504B, 604A, 604B, 704A, 704B, 804A, 804B, 904) comprises at least one physisorbent.

9. The device according to claim 8, wherein the at least one physisorbent is selected from the group consisting of silica gel, zeolite, aluminosilicate and MOF (Metal Organic Framework).

10. A process for the production of carbon dioxide, comprising the steps of: - drying a gaseous medium, - Adsorbing CO2 from the gaseous medium in a CO2 unit (104, 204A, 304, 504A, 604A, 704A, 804A, 904), and - simultaneous recovery of CO2 by desorbing CO2 in a CO2 unit (104, 204B, 304, 504B, 604B, 704B, 804B, 904).

11. The method of claim 10, further comprising the step of cooling the gaseous medium prior to adsorbing the CO2.

12. The method according to claim 10 or 11, further comprising the step of heat recovery, in particular comprising the step of heat recovery by means of a heat exchanger unit (105, 205, 505, 605, 705, 805).

13. The method according to at least one of claims 10 to 12, further comprising the step of transporting the gaseous medium by means of a blower.

14. The method according to at least one of claims 10 to 13, wherein the desorption of the adsorbed CO2 is carried out by heating.

15. Use of a device according to at least one of claims 1 to 9, or of a process according to at least one of claims 10 to 14 for obtaining carbon dioxide from a gaseous medium.

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