Method for desorbing co2 sorbed at a sorption means

Abstract

Proposed is a method (100) for desorbing CO2 sorbed at a sorption means, wherein the sorption means is arranged in a separation chamber (14) of a CO2 separation device (10), the method comprising the following steps: - generating a negative pressure in the separation chamber (14) by means of a pump unit in order to remove atmospheric oxygen and then desorbed CO2 from the separation chamber (14); - metering liquid water into the separation chamber (14), which has negative pressure, by means of a water metering unit (30) depending on a remaining amount of atmospheric oxygen in the separation chamber (14) such that the liquid water evaporates in the separation chamber (14) in order to force the remaining amount of atmospheric oxygen out of the separation chamber (14); and - heating the sorption means during generation (106) of the negative pressure by means of a temperature control unit, in particular an electric temperature control unit and / or a temperature control circuit in order to desorb the sorbed CO2 from the sorption means.

Description

[0001] Description

[0002] title

[0003] Process for desorbing CO2 sorbed on a sorbent

[0004] State of the art

[0005] The invention relates to a method for desorbing CO2 sorbed on a sorbent and a CO2 separation device for desorbing CO2 sorbed on a sorbent.

[0006] In order to limit the warming of the Earth's atmosphere, so-called DAC systems (Direct Air Capture) are used to separate or remove CO2 (carbon dioxide) from the air.

[0007] WO 2021 / 239747 A1 discloses a process for the adsorption and desorption of a sorbent used in cyclic adsorption-desorption to capture CO2 directly from atmospheric ambient air or highly diluted sources. After the adsorption chamber is closed, water vapor is injected to displace residual oxygen, which would lead to adsorbent material degradation at elevated temperatures. Furthermore, the water vapor is used to directly heat the adsorbent material and provide the energy for desorption. Finally, the water vapor serves as an inert gas with which the CO2 is pumped out of the chamber.

[0008] Disclosure of the invention

[0009] The present invention relates to a method for desorbing CO2 sorbed on a sorbent, wherein the sorbent is arranged in a separation chamber of a CO2 separation device, comprising the steps of: - generating a negative pressure in the separation chamber by means of a pump unit in order to remove atmospheric oxygen and subsequently desorbed CO2 from the separation chamber;

[0010] - Dosing liquid water into the separation chamber having the negative pressure by means of a water dosing unit depending on a residual amount of atmospheric oxygen in the separation chamber such that the liquid water in the separation chamber evaporates in order to displace the residual amount of atmospheric oxygen from the separation chamber; and

[0011] - Heating the sorbent while generating the negative pressure by means of a temperature control unit, in particular an electrical temperature control unit and / or a temperature control circuit, in order to desorb the sorbed CO2 from the sorbent.

[0012] The present invention further relates to a control unit which is configured to control and / or regulate the steps of the method described above.

[0013] The present invention also relates to a CO2 separation device for desorbing CO2 sorbed on a sorbent, with

[0014] - a separation chamber for holding the sorbent;

[0015] - a pumping unit for generating a negative pressure in the separation chamber in order to remove atmospheric oxygen and subsequently desorbed CO2 from the separation chamber;

[0016] - a water dosing unit for dosing liquid water into the separation chamber depending on a residual amount of atmospheric oxygen such that the liquid water in the separation chamber evaporates in order to displace the residual amount of atmospheric oxygen from the separation chamber;

[0017] - a temperature control unit, in particular an electrical temperature control unit and / or a temperature control circuit, for heating the sorbent in the separation chamber in order to desorb the sorbed CO2 from the sorbent. According to the invention, liquid water is metered into the separation chamber in a defined manner, resulting in atomization and in-situ evaporation of the metered water in the separation chamber, displacing a residual amount of atmospheric oxygen from the separation chamber, and heating the sorbent for the desorption process by means of a separate temperature control unit.

[0018] This allows the advantages of water vapor to be utilized for inerting and desorption, whereby only a comparatively small defined amount of liquid water to be evaporated is required, since the desorption energy is supplied by means of the separate temperature control unit, e.g. in the form of electrical heating.

[0019] Consequently, in contrast to the prior art mentioned above, a steam generator for generating large quantities of steam can be dispensed with. This allows the size of the vacuum pump to be reduced, allowing the overall system to be designed more compactly. Since the precise dosing of steam is complex and requires measuring and metering devices as well as thermally insulated lines leading to a central steam generation system, the inventive dosing of liquid water and the use of a separate temperature control unit is also more energy-efficient and easier and more cost-effective to implement and control.

[0020] Desorption can be chemical desorption and / or physical desorption. In this process, the CO2 can be released by applying energy or heat to the sorbent.

[0021] The sorbent is preferably a solid (appropriately functionalized) sorbent, in particular a solid adsorbent and / or a solid absorbent. The sorbent can, for example, comprise a fibrous or nonwoven solid as a carrier structure with a base material selected from the group consisting of: resins, polymers, ceramics, zeolites, silicates, organometallic compounds, organic materials such as cellulose or activated carbon, and combinations thereof. The base material can, in turn, be specifically functionalized with amines, potassium carbonate, or other components designed to chemically or physically bind CO2.

[0022] An example is the CO2 adsorption / absorption on amine compounds, e.g. Lewatit VP OC 1065, in which CO2 and water initially adhere to molecules and then CO2 forms a strong bond through chemical reaction with the cooperation of water in order to be effective even at low CO2 concentrations.

[0023] According to the invention, a negative pressure is created in the separation chamber by means of a pump unit in order to remove or pump out atmospheric oxygen present in the separation chamber and subsequently desorbed CO2 from the separation chamber. The negative pressure is, in particular, a vacuum. In other words, the atmospheric oxygen or air is first pumped out of the separation chamber as far as possible, whereby at a chamber pressure of, for example, 100 mbar, a residual amount of atmospheric oxygen still remains according to the partial pressure.

[0024] The atmospheric oxygen is preferably the oxygen of the air from which the CO2 was previously sorbed, i.e. which was previously fed to the separation chamber for sorption or which previously flowed through the separation chamber.

[0025] It is therefore advantageous if an air stream is previously fed into the separation chamber for the sorption of the CO2 on the sorbent, ie the air flows through the separation chamber, and the separation chamber is closed to the environment after the sorption process has ended.

[0026] The pump unit can, for example, be connected to a vacuum connection of the separation chamber. The separation chamber is preferably designed to be closable by means of valves, so that a vacuum can be generated therein by means of the pump unit. In this case, the separation chamber can have a valve unit with a plurality of, in particular controllable, valves in order to close the separation chamber for desorption. The valve unit can have an inlet valve, which is arranged in an inlet channel for the supplied air stream and is designed to close the inlet channel and to isolate the separation chamber upstream. The valve unit can further have an outlet valve, which is arranged in an outlet channel for the CO2-reduced air stream and is designed to close the outlet channel and to isolate the separation chamber downstream.The valve unit may also comprise a CO2 valve arranged in a CO2 outlet channel and configured to open the CO2 outlet channel in order to selectively discharge or pump out desorbed CO2 from the separation chamber.

[0027] Liquid water is then metered, i.e., introduced or injected, into the separation chamber using a water dosing unit to displace any residual atmospheric oxygen from the separation chamber. The negative pressure in the separation chamber is maintained, although the negative pressure value can, understandably, change and therefore does not necessarily have to remain constant.

[0028] The water dosing unit is therefore designed to dose liquid water into the separation chamber, i.e., to introduce or inject it in a defined manner. For this purpose, the water dosing unit can have at least one spray nozzle, in particular a plurality of spray nozzles. The spray nozzles can be distributed throughout the separation chamber.

[0029] The liquid water is metered in depending on the residual amount of atmospheric oxygen in the separation chamber, so that the liquid water evaporates in the separation chamber, thereby displacing the residual amount of atmospheric oxygen from the separation chamber. The liquid water is metered in such a way that it atomizes in the separation chamber and, depending on pressure and temperature, also evaporates in situ. The liquid water can be metered or injected into the separation chamber at several points.

[0030] The step of dosing the liquid water can take place or be carried out during the step of generating the negative pressure. In other words, in a first alternative, the step of generating the negative pressure is carried out continuously, so that the pump unit continues to pump out even while the liquid water is being dosed. In a second alternative, the step of generating the negative pressure is interrupted during the step of dosing the liquid water, so that although a negative pressure still exists or is present in the separation chamber, no suction or pumping out takes place or is carried out by means of the pump unit. In both alternatives, the negative pressure in the separation chamber is maintained, although the negative pressure value can understandably change and therefore does not have to remain constant.

[0031] In this case, the amount of liquid water is preferably selected depending on the residual amount of atmospheric oxygen in the separation chamber. The amount of liquid water is further preferably selected depending on the negative pressure generated and / or a temperature in the separation chamber. The amount of liquid water is preferably selected such that only as much water vapor volume is generated as is necessary to displace the residual amount of atmospheric oxygen.

[0032] At a pressure of 50 mbar, for example, water already boils at 32.9 °C, so it is sufficient to dose slightly warmed water. If water at, for example, 50 °C is dosed at a pressure of 100 mbar (boiling point 45.8 °C), the water evaporates.

[0033] It is advantageous if, in the dosing step, the liquid water is dosed continuously or periodically depending on the residual amount of atmospheric oxygen in the separation chamber.

[0034] It is also advantageous if the dosing step is carried out until a residual quantity threshold is reached. The residual quantity threshold is selected such that no degradation of the sorbent occurs upon heating.

[0035] It is also advantageous if, in the dosing step, the liquid water is applied - to the sorbent; and / or - to a heatable carrier on which the sorbent is applied; and / or

[0036] - sprayed onto a heatable wall, in particular a heatable chamber wall of the separation chamber, and / or

[0037] - is dosed, in particular injected, into a sorbent-free anteroom of the separation chamber.

[0038] The residual amount of atmospheric oxygen in the separation chamber is preferably determined by means of an oxygen sensor, in particular in the area of ​​the vacuum connection for the pump unit.

[0039] Subsequently, while the negative pressure is generated, the sorbent is heated by a temperature control unit, e.g., to 100 °C, to desorb the sorbed CO2 from the sorbent. This temperature control unit is separate from the water dosing unit. Furthermore, the temperature control unit understandably does not have a steam generator for providing steam. Rather, the temperature control unit preferably comprises or is an electrical temperature control unit and / or a temperature control circuit.

[0040] Accordingly, the desorbed CO2 and the co-desorbed water (co-adsorption of CO2 and H2O) are pumped out, whereby, contrary to WO 2021 / 239747 A1 described above, additionally introduced water vapor does not need to be removed. Due to the temperature and the water desorbed in parallel with the CO2, a continuous mixture of CO2 and H2O is formed in the separation chamber until the desorption process is complete, i.e., equilibrium is established by pumping out at, for example, 100 mbar and a temperature of 100 °C.

[0041] It is advantageous if the heating step is carried out depending on the residual amount of atmospheric oxygen in the separation chamber, in particular

[0042] - is only carried out at and / or below a residual quantity threshold; or - is carried out in such a way that above a residual quantity threshold the sorbent is heated to a first temperature and from and / or below the residual quantity threshold to a higher second temperature.

[0043] Furthermore, it is advantageous if further dosing of liquid water into the separation chamber is carried out by means of the water dosing unit after the desorption process has ended, but while the negative pressure is being generated, in order to cool the separation chamber. The further dosing of liquid water is carried out in particular in such a way that the liquid water in the separation chamber evaporates and condensation of the evaporated water is largely avoided. It is also advantageous if the amount of liquid water is selected depending on the difference between the actual temperature in the separation chamber and the target temperature.

[0044] In other words, after the desorption process, a defined amount of liquid water is metered in to cool the system, as this evaporates and absorbs heat during evaporation. Since this primarily produces water vapor and the negative pressure is still generated, this continues to be pumped out and discarded. With precise metering of liquid water and recording of the temperature in the separation chamber, condensation can be avoided because an equilibrium is established, i.e. the system is "dry" at e.g. 100 mbar and 60 °C. When a temperature is reached which is not critical for air contact of the sorbent, e.g. <60 °C, the water metering is stopped and the separation chamber is opened again to the atmosphere.

[0045] Optionally, the water dosing can be stopped and the pressure further reduced to 50 mbar so that the residual water evaporates safely.

[0046] The control unit according to the invention is configured to control and / or regulate the steps of the method described above. The control unit is preferably configured to control and / or regulate the entire sorption and desorption process. The control unit can be configured to be connected to other control units and / or a central control unit of the CO2 separation device or a higher-level system via wireless transmission such as Wi-Fi, Bluetooth, near-field communication, etc.

[0047] The CO2 separation device is designed to desorb CO2 sorbed on a sorbent. The CO2 separation device is particularly designed to release or dissolve the CO2 from the sorbent by means of a desorption process in which the CO2 is released by introducing energy or heat into the sorbent. Accordingly, the desorption process can in particular comprise at least one of the following processes or combinations thereof:

[0048] - chemical desorption process

[0049] - physical desorption process

[0050] The CO2 separation device is preferably further configured to sorb CO2 from a supplied air stream using a sorption process. The CO2 separation device is particularly configured to separate the CO2 from the supplied air stream using a sorption process, in which the separation occurs with the release of energy or heat to the air stream. The separation process preferably comprises an adsorption process and / or an absorption process. Accordingly, the sorption process can comprise at least one of the following processes or mixed forms thereof:

[0051] - chemical adsorption process

[0052] - physical adsorption process

[0053] - chemical absorption process

[0054] - physical absorption process

[0055] The CO2 separation device is preferably designed to carry out the sorption process and the desorption process cyclically. The basic mode of operation of the CO2 separation device can, for example, be analogous to WO 2021 / 239747 A1 mentioned above. In the context of the present invention, the term "supply" or "supplied" primarily encompasses an actively carried out or initiated and thus technically controlled or regulated supply of the air flow by means of a blower unit or fan unit of the CO2 separation device. However, the term "supply" or "supplied" can also encompass a passively carried out or initiated supply of the air flow, without departing from the scope of the present invention. Consequently, the air flow can be supplied in any desired manner, e.g., in a natural manner (as wind).

[0056] The CO2 separation device may further comprise at least one of the following units:

[0057] - control unit described above; and / or

[0058] - Blower unit, in particular with a plurality of fans for supplying the air flow.

[0059] The CO2 separation device can be mobile or stationary. In particular, the CO2 separation device or CO2 separation system can be part of a building's air conditioning system, especially integrated into a building's air conditioning system. The separation chamber of the CO2 separation device can be integrated into the building's air conditioning circuit, allowing the fan already present there to quickly cool the sorbent, since there are no large heat capacities in the system to dampen it. The air conditioning system can also be temporarily set to a lower temperature for cooling purposes, if this is advantageous in terms of overall energy efficiency.

[0060] Drawings

[0061] The invention is explained in more detail below with reference to the accompanying drawings. They show:

[0062] Fig. 1 is a schematic representation of a CO2 separation device according to the invention; and

[0063] Fig. 2 shows a flow diagram of a method according to an embodiment. Fig. 1 shows a CO2 separation device, which is designated in its entirety by the reference number 10.

[0064] The CO2 separation device 10 is designed to separate CO2 (carbon dioxide) from an air stream 12 supplied by a blower unit (not shown) by means of a cyclically carried out adsorption-desorption process.

[0065] For this purpose, the CO2 separation device 10 has a separation chamber 14 for receiving a sorbent (not shown). The separation chamber 14 has an inlet valve 16 on an inlet channel 18 for the sucked-in air stream 12, which is designed to close the inlet channel 18 and isolate the separation chamber 14 upstream. The separation chamber 14 further has an outlet valve 20 on an outlet channel 22 for the CO2-reduced air stream 12', which is designed to close the outlet channel 22 and isolate the separation chamber 14 downstream. The separation chamber 14 also has a CO2 valve 24, which is arranged in a CO2 outlet channel 26 and is designed to open the CO2 outlet channel 26 in order to discharge adsorbed, ie bound / filtered and desorbed, ie released, CO2 from the separation chamber 14 in a targeted manner into a system 28 for permanent CO2 removal with CO2 conditioning.

[0066] The CO2 separation device 10 further comprises a pump unit for generating a negative pressure in the separation chamber 14 in order to discharge or pump out a residual amount of atmospheric oxygen and subsequently desorbed CO2 from the separation chamber 14 through the CO2 outlet channel 26.

[0067] The CO2 separation device 10 also includes a water dosing unit 30 for dosing liquid water into the separation chamber 14. The water dosing unit 30 is configured to dose the liquid water into the separation chamber 14 in such a way that it evaporates and displaces a residual amount of atmospheric oxygen from the separation chamber 14 while generating the negative pressure. The CO2 separation device 10 further includes an electrical temperature control unit (not shown) for heating the sorbent in the separation chamber 14 to desorb the sorbed CO2 from the sorbent.

[0068] Fig. 2 shows a flow diagram of an embodiment of the approach presented here as a method 100 for desorbing CO2 sorbed on a sorbent, wherein the sorbent is arranged in a separation chamber 14 of a CO2 separation device 10. The method 100 comprises a step of generating 106 a negative pressure in the separation chamber 14 by means of a pump unit in order to discharge atmospheric oxygen and subsequently desorbed CO2 from the separation chamber 14. The method 100 further comprises a step of dosing 108 liquid water into the separation chamber 14 having the negative pressure by means of a water dosing unit 30 as a function of a residual amount of atmospheric oxygen in the separation chamber 14 such that the liquid water in the separation chamber 14 evaporates in order to displace the residual amount of atmospheric oxygen from the separation chamber 14.The method 100 further comprises a step of heating 110 the sorbent during the generation 106 of the negative pressure by means of a temperature control unit, in particular an electrical temperature control unit and / or a temperature control circuit, in order to desorb the sorbed CO2 from the sorbent.

[0069] The method 100 further comprises an optional step of supplying 102 an air stream 12 into the separation chamber 14 for sorption of the CO2 on the sorbent and an optional step of closing 104 the separation chamber 14 from the environment after completion of the sorption process.

[0070] If an embodiment comprises an “and / or” link between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature and according to another embodiment has either only the first feature or only the second feature.

Claims

Claims 1 . A method (100) for desorbing CO2 sorbed on a sorbent, wherein the sorbent is arranged in a separation chamber (14) of a CO2 separation device (10), comprising the steps: - generating (106) a negative pressure in the separation chamber (14) by means of a pumping unit in order to remove atmospheric oxygen and subsequently desorbed CO2 from the separation chamber (14); - Dosing (108) of liquid water into the separation chamber (14) having the negative pressure by means of a water dosing unit (30) depending on a residual amount of atmospheric oxygen in the separation chamber (14) such that the liquid water in the separation chamber (14) evaporates in order to displace the residual amount of atmospheric oxygen from the separation chamber (14); and - heating (110) the sorbent during the generation (106) of the negative pressure by means of a temperature control unit, in particular an electrical temperature control unit and / or a temperature control circuit, in order to desorb the sorbed CO2 from the sorbent.

2. Method (100) according to claim 1, characterized in that the step of generating (106) the negative pressure is interrupted or carried out continuously during the step of dosing (108) the liquid water.

3. Method (100) according to claim 1 or 2, characterized in that the heating step (110) is carried out depending on the residual amount of atmospheric oxygen in the separation chamber (14), in particular - is only carried out from and / or below a residual quantity threshold; or - is carried out in such a way that above a residual quantity threshold the sorbent is heated to a first temperature and from and / or below the residual quantity threshold to a higher second temperature.

4. Method (100) according to one of the preceding claims, characterized in that in the dosing step (108) the amount of liquid water is selected as a function of the residual amount of atmospheric oxygen in the separation chamber (14).

5. The method (100) according to claim 4, characterized in that in the dosing step (108) the amount of liquid water is further selected as a function of the negative pressure generated and / or a temperature in the separation chamber (14).

6. Method (100) according to one of the preceding claims, characterized in that in the dosing step (108) the liquid water is dosed continuously or periodically depending on the residual amount of atmospheric oxygen in the separation chamber (14).

7. Method (100) according to one of the preceding claims, characterized in that the dosing step (108) is carried out until a residual quantity threshold is reached.

8. Method (100) according to one of the preceding claims, characterized in that in the dosing step (108) the liquid water - on the sorbent; and / or - on a heatable carrier on which the sorbent is applied; and / or - sprayed onto a heatable wall, in particular a heatable chamber wall of the separation chamber (14), and / or - is dosed, in particular injected, into a sorbent-free anteroom of the separation chamber.

9. Method (100) according to one of the preceding claims, characterized in that the residual amount of atmospheric oxygen in the separation chamber (14) is determined by means of an oxygen sensor, in particular in the region of a vacuum connection for the pump unit.

10. Method (100) according to one of the preceding claims, characterized by the steps: - feeding (102) an air stream (12) into the separation chamber (14) for sorption of the CO2 on the sorbent; and - Closing (104) the separation chamber (14) from the environment after completion of the sorption process.

11. Method (100) according to one of the preceding claims, characterized by the further step: - further dosing of liquid water into the separation chamber (14) by means of the water dosing unit (30) after completion of the desorption process in order to cool the separation chamber (14), in particular in such a way that the liquid water in the separation chamber (14) evaporates and condensation of the evaporated water is largely avoided.

12. The method (100) according to claim 11, characterized in that in the step of further dosing, the amount of liquid water is selected as a function of the difference between an actual temperature in the separation chamber (14) and a desired temperature.

13. Control unit which is configured to control and / or regulate the steps of the method (100) according to one of the preceding claims.

14. CO2 separation device (10) for desorbing CO2 sorbed on a sorbent, with - a separation chamber (14) for receiving the sorbent; - a pump unit for generating a negative pressure in the separation chamber (14) in order to remove atmospheric oxygen and subsequently desorbed CO2 from the separation chamber (14); - a water dosing unit (30) for dosing liquid water into the separation chamber (14) as a function of a residual amount of atmospheric oxygen such that the liquid water in the separation chamber evaporates in order to displace the residual amount of atmospheric oxygen from the separation chamber; - a temperature control unit, in particular an electrical temperature control unit and / or a temperature control circuit, for heating (110) the sorbent in the separation chamber (14) in order to desorb the sorbed CO2 from the sorbent.

15. CO2 separation device (10) according to claim 14 with a control unit according to claim 13.

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