Method for operating a co2 separation device

Abstract

The invention relates to a method for operating a CO2 separation device (10) for separating CO2 from a supplied gas flow (14), in particular an air flow (14) of an environment, comprising at least one chamber (16) for receiving a CO2 separation means (19) for a CO2 separation process, in particular a sorption process, and a CO2 release process, in particular a desorption process, wherein CO2 released during the release process is cooled and then recirculated back into the chamber (16) in order to cool the CO2 separation means (19) for the subsequent CO2 separation process.

Description

[0001] R.410913

[0002] - 1 -

[0003] Description

[0004] title

[0005] Method for operating a CO2-

[0006] State of the art

[0007] The invention relates to a method for operating a CO2 separation device for separating CO2 from a supplied gas stream, in particular an air stream from an environment, comprising at least one chamber for receiving a CO2 separation agent for a CO2 separation process, in particular a sorption process, and a CO2 release process, in particular a desorption process. The invention further relates to a CO2 separation device for separating CO2 from a supplied gas stream, in particular an air stream from an environment, comprising at least one chamber for receiving a CO2 separation agent for a CO2 separation process, in particular a sorption process, and a CO2 release process, in particular a desorption process.

[0008] To limit the warming of the Earth's atmosphere, so-called DAC (Direct Air Capture) systems are used to separate or remove CO2 (carbon dioxide) from the air.

[0009] Since the binding of CO2 and, if present, water to an adsorbent material depends on temperature, pressure, concentration, humidity, etc., all adsorption and desorption systems cyclically establish different conditions in order to separate CO2 through the resulting hysteresis. To adjust the desorption conditions, the adsorbent material must be temporarily sealed off from the environment and is therefore located in a chamber.

[0010] The chamber typically goes through the following steps cyclically: (1) Adsorption of ambient air with the chamber open; R.410913

[0011] - 2 -

[0012] (2) Sealing the chamber and heating the adsorber material and the metallic chamber structure;

[0013] (3) Desorption of the CO2 and the bound water by supplying heat (e.g. in a range of greater than or equal to 90°C to less than or equal to 120°C, on average therefore approx. 105°C) under exclusion of oxygen to avoid degradation of the adsorber material, and at reduced pressure (e.g. in a range of greater than or equal to 50 mbar to less than or equal to 400 mbar) and pumping out the CO2 and the water vapor by means of a vacuum pump;

[0014] (4) active cooling of the adsorber material and the chamber and optionally drying of the adsorber material to below a critical temperature (e.g. in a range of greater than or equal to 50°C to less than or equal to 60°C) below which contact with ambient air no longer leads to increased degradation of the adsorber material by atmospheric oxygen;

[0015] (5) Opening the chamber to the environment, cooling to ambient temperature and thus resuming adsorption of CO2 and water from the ambient air.

[0016] For example, CO2 is preferably adsorbed under ambient air conditions, and it has been known for some time that the presence of humidity promotes adsorption in many adsorbent materials.

[0017] As explained previously, heated adsorbent material must be cooled before opening the chamber to prevent oxidation by oxygenated air. Cooling with cooling coils requires a significant additional investment. Cooling using the latent heat of vaporization of water means that a sufficient quantity of water must remain in the system after CO2 desorption or be added separately to achieve cooling. This results in high operating costs and also presents technical challenges, as cooling through evaporating water is limited by its vapor pressure. Technically, in large DAC systems, a negative pressure of, for example, 50 mbar can be set within a sufficiently short time, so that the vapor pressure from evaporation at equilibrium is limited to a lower limit of 32 °C.If one does not want to wait indefinitely, only temperatures around 40 to 50 °C can be achieved, although the degradation of the adsorber material when opening the flaps after desorption is reduced to R.410913.

[0018] - 3 -

[0019] Oxygen from the ambient air is prevented, however, the heating energy between ambient temperature and the lower temperature value is lost during cooling, e.g. 40 °C in each cycle.

[0020] WO 2021 / 259760 therefore describes that the cooling and drying of the adsorber material can also be carried out by applying negative pressure, since the required heat of vaporization cools the material.

[0021] WO 2020 / 212146 A1 discloses a DAC (Direct Air Capture) system with a container solution, wherein six separation chambers are arranged in series and can be operated in parallel. The containers can either be coupled together and fed to a vacuum pump for desorption or each can be connected to its own vacuum pump.

[0022] WO 2021 / 239747 A1 discloses a process for the adsorption and desorption of a sorbent used in cyclic adsorption-desorption for capturing CO2 directly from atmospheric air or highly dilute sources. In this process, after sealing the adsorption chamber, water vapor is injected to displace residual oxygen, which would lead to degradation of the adsorbent material at elevated temperatures.

[0023] Disclosure of the invention

[0024] The present invention relates to a method of the type described in the introduction, wherein CO2 released by the release process is cooled and then recirculated back into the chamber to cool the CO2 separation agent for the following CO2 separation process.

[0025] The present invention further relates to a CO2 separation device of the type described in the introduction, wherein the CO2 separation device is configured to cool the CO2 released by the release process and subsequently recirculate it back into the chamber to cool the CO2 separation agent for the subsequent CO2 separation process. R.410913

[0026] - 4 -

[0027] The core of the invention lies in using the recovered, released CO2, for example via a suitable blower, at the end of the desorption process to cool the CO2 separation agent or the sorption materials. This significantly increases energy efficiency, as even the heat losses between ambient temperature and, for example, a chamber temperature of 40 °C—the practically achievable limit of evaporative cooling—can be compensated for using this type of cooling. Furthermore, the active cooling reduces the cycle time, so that, with a suitable system design, the same amount of CO2 can generally be recovered per day. This is particularly advantageous when using CO2 separation agents or sorption materials that have a high capacity for CO2 in the presence of moisture (H2O). In contrast to the prior art, this avoids the need for the deliberate evaporation of water after the desorption process.

[0028] Preferably, the supplied gas stream comprises an air stream of cold ambient air, i.e., ambient air with a temperature of 20°C or less. This allows for significant energy savings, particularly at low ambient temperatures of 20°C or less.

[0029] According to the invention, the CO2 released during the release process is first cooled. Preferably, the released CO2 is cooled to essentially ambient temperature in order to cool the CO2 separation agent to a defined temperature, e.g., greater than or equal to 40°C or greater than or equal to the ambient temperature.

[0030] The cooled CO2 is then recirculated back into the chamber to cool the CO2 separation fluid for the subsequent CO2 separation process. As long as the CO2 remains warm, CO2 continues to evaporate from the separation fluid during recirculation. It should be noted that the recirculated CO2 is not reabsorbed by the separation fluid, since the atmosphere still contains CO2 at equilibrium (e.g., 100 mbar absolute atmosphere: 33% CO2, 77% water).

[0031] In this process, the released CO2 is preferably recirculated into the chamber by means of a recirculation line and a recirculation fan. Consequently, R.410913

[0032] - 5 - only a recirculation line, a recirculation fan and appropriate recirculation valves are required to cool a CO2 separator, which can absorb a large amount of CO2 at high humidity, with (dry) CO2.

[0033] Advantageously, any water present in the released CO2 is removed before recirculation, in particular by condensation, in order to obtain dry CO2 for subsequent cooling.

[0034] Advantageously, the cooling of the CO2 and / or the removal of the water is carried out before or during a compression process of the released CO2, particularly by means of a cooler in the CO2 separation device. Consequently, the CO2 is only "circulated" via a heat exchanger, so that, advantageously, hardly any pressure change work is required in addition to the low pressure losses in the system due to pipes, sorption structure resistance, and resistance in the cooler or heat exchanger.

[0035] It is also advantageous if the released CO2 is temporarily stored in an intermediate storage tank, at least at atmospheric pressure, in order to continuously supply a compressor of the CO2 separation device.

[0036] The CO2 separation device is designed and configured to separate CO2 from a supplied gas stream, in particular an air stream, from an environment (preferably the CO2 separation device itself). The CO2 separation device is preferably designed as a Direct Air Capture (DAC) device or system.

[0037] Within the scope of the present invention, the term "supply" or "supplied" primarily encompasses an actively initiated or caused, and thus technically controlled or regulated, supply of the gas or 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 caused supply of the gas or air flow, without thereby exceeding the scope of the present invention (see R.410913).

[0038] - 6 - exit. Consequently, the airflow can be supplied in any way, e.g. naturally (as wind).

[0039] According to the invention, the CO2 separation device is configured to cool the CO2 released during the release process and then recirculate it back into the chamber to cool the CO2 separation agent for the subsequent CO2 separation process. In particular, the CO2 separation device is designed to cool the released CO2 to essentially ambient temperature in order to cool the CO2 separation agent to a defined temperature, e.g., greater than or equal to 40°C or greater than or equal to the ambient temperature.

[0040] For this purpose, the CO2 separation device preferably has a recirculation line and a recirculation blower for recirculating the released CO2 into the chamber.

[0041] Preferably, the CO2 separation device has a cooler upstream of a pump unit of the CO2 separation device for cooling the CO2 and / or for removing water from the released CO2.

[0042] Alternatively or additionally, the CO2 separation device has an intermediate storage unit, particularly along the recirculation line, for temporarily storing the released CO2 at at least atmospheric pressure.

[0043] The CO2 separation device has at least one chamber in which the CO2 separation agent is received or contained. The CO2 separation device preferably has a plurality of chambers, which may be arranged adjacent to one another and / or side by side, or, if installed separately, fluidically connected to one another.

[0044] At least one chamber is preferably designed for the alternating cyclical execution of the CO2 separation process and the CO2 release process. In other words, the chamber, or the plurality of chambers, can be operated individually or in groups in parallel in a CO2 release mode and a CO2 separation mode ("fixed bed"). Here, the CO2- R.410913

[0045] - 7 -

[0046] The release mode and the CO2 separation mode are repeated cyclically. The basic operation of the CO2 separation device can be carried out, for example, analogously to the aforementioned WO 2020 / 212146 A1.

[0047] The CO2 release process is carried out under reduced pressure and at a temperature higher than ambient. Accordingly, the CO2 release process is preferably carried out using a pump unit or vacuum unit to release CO2 bound in the CO2 separation medium, which was previously bound as a result of a CO2 separation process, in particular a sorption process. The CO2 is, understandably, temporarily bound. Within the scope of the present invention, the term "release" encompasses any meaningful method of releasing or expelling CO2 (carbon dioxide) from the CO2 separation medium, wherein a dissolution and / or release and / or discharge of CO2 molecules from the CO2 separation medium occurs. In this process, the CO2 is released or dissolved from the CO2 separation medium, in particular by introducing energy or heat into it.

[0048] The CO2 release mode is preferably a desorption mode. Accordingly, the release of CO2 can be achieved in particular by means of at least one of the following processes or combinations thereof:

[0049] - chemical desorption process

[0050] - physical desorption process

[0051] The CO2 separation process is carried out at a higher pressure, particularly ambient pressure, and a lower temperature, particularly ambient temperature, compared to the CO2 release process. Within the scope of the present invention, the term "separation" encompasses any meaningful method of separating or removing CO2 (carbon dioxide) from the gas or air stream, involving the binding, adhesion, storage, and / or absorption of CO2 molecules by the CO2 separation agent.

[0052] The CO2 separation mode is preferably a sorption mode, which in particular includes an adsorption process and / or an absorption process R.410913

[0053] - 8 - includes. Accordingly, the separation of CO2 can be carried out in particular by means of at least one of the following processes or mixtures thereof:

[0054] - chemical adsorption process

[0055] - physical adsorption process

[0056] - chemical absorption process

[0057] - physical absorption process

[0058] The CO2 separation device can include a valve unit with a plurality of valves, particularly controllable ones, for closing the at least one chamber for the CO2 release mode. The valve unit can include an inlet valve, which is arranged in an inlet channel for the supplied or drawn-in gas or air flow and is configured to close the inlet channel and isolate the chamber upstream. The valve unit can further include an outlet valve, which is arranged in an outlet channel for the CO2-reduced gas or air flow and is configured to close the outlet channel and isolate the chamber downstream. The valve unit can also include a CO2 discharge valve, which is arranged in a CO2 discharge channel for removing separated CO2 and is configured to open the CO2 discharge channel in order to selectively discharge the separated / bound and re-released CO2 from the chamber.

[0059] The CO2 separation agent is designed for separating CO2 from a supplied gas or air stream. The CO2 separation agent is preferably solid. It can be, for example, particulate, fibrous, or mat-shaped. The CO2 separation agent can, in particular, comprise a solid (appropriately functionalized) sorbent, such as an adsorbent and / or an absorbent. Accordingly, the CO2 separation agent can, for example, have a particulate, fibrous, or nonwoven solid as a support 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.The CO2 separation agent may also be designed to be permeable to air. R.410913.

[0060] - 9 -

[0061] The CO2 separation agent can comprise or be in the form of a granular ion exchange resin. The CO2 separation agent can, for example, comprise or consist of granular Lewatit VP OC 1065 or Zeolite X13.

[0062] The CO2 separation device may further comprise at least one of the following units:

[0063] - Blower unit, in particular with a large number of fans for supplying the gas or air flow;

[0064] - Steam generator for providing steam for the CO2 release mode or desorption mode;

[0065] - Inerting unit for supplying an inert gas stream, such as nitrogen, oxygen-free air and / or water vapor, to remove oxygen before the CO2 release mode or desorption mode to protect the CO2 combustion medium from chemical degradation;

[0066] - Heating unit for additional heating of the CO2 separation agent for the CO2 release mode or desorption mode;

[0067] - Cooling unit for additional cooling of the CO2 separation agent for the CO2 separation mode or sorption mode;

[0068] - Material conveying unit for conveying the CO2 separation agent through the chamber;

[0069] - Sensor unit for CO2 separation and CO2 release modes;

[0070] - Control unit for controlling and / or regulating the CO2 separation and CO2 release mode.

[0071] 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 WLAN, Bluetooth, Near-Field Communication, etc. It should be noted that, within the scope of this application, the term "control" also includes regulating the respective device and / or unit.

[0072] The CO2 separation device is preferably designed as a stationary unit. In particular, the CO2 separation device can be part of a building climate control system, especially within a building climate control system (R.410913).

[0073] - 10 - be integrated. In this case, the chambers of the CO2 separation device can be integrated into the building's air conditioning circuit.

[0074] Drawings

[0075] The invention is explained in more detail below with reference to the accompanying drawings. These show:

[0076] Fig. 1 shows a basic structure of a CO2 system according to the invention.

[0077] Separating device; and

[0078] Fig. 1 shows a basic structure of a CO2 separation device, which is designated as a whole by reference numeral 10. The CO2 separation device 10 is designed to separate CO2 (carbon dioxide) from an air stream 14 supplied by a blower unit 12 by means of cyclically executable CO2 separation modes or CO2 sorption modes and CO2 release modes or CO2 desorption modes.

[0079] For this purpose, the CO2 separation device 10 has a chamber 16 for receiving a CO2 separation module with a CO2 separation agent 18 or sorbent 18. The chamber 16 has an inlet valve 20 on an inlet channel 22 for the aspirated airflow 14, which is configured to close the inlet channel 22 and isolate the chamber 16 upstream from the environment. The chamber 16 also has an outlet valve 24 on an outlet channel 26 for the CO2-reduced airflow 14', which is configured to close the outlet channel 26 and isolate the chamber 16 downstream from the environment. The chamber 16 also has a CO2 valve 28, which is arranged in a CO2 discharge channel 30 and is designed to open the CO2 discharge channel 30 in order to discharge separated, i.e. sorbed and released, i.e. desorbed CO2 and, if applicable, water vapor from the chamber 16.

[0080] The released CO2 and water vapor are pumped out of chamber 16 by means of a pump unit 32 or vacuum pump 32, with a cooler 34 or water vapor condenser 34 being connected upstream of the pump unit 32. R.410913

[0081] - 11 -

[0082] According to the invention, the CO2 separation device 10 is configured to cool the CO2 released by the release process (to essentially ambient temperature) and then recirculate it back into the chamber 16 in order to cool the CO2 separation agent 19 to a defined temperature, e.g. of greater than or equal to 40°C, for the following CO2 separation process.

[0083] For this purpose, the CO2 separation device 10 has a recirculation line 36 with a recirculation blower 38 for recirculating the released CO2 into the chamber 16. The recirculation line 36 is designed to direct the released CO2, which has been dried by the cooler 34, back into the chamber 16 in order to cool the CO2 combustion medium 19.

[0084] Furthermore, the CO2 separation device 10 has an intermediate storage tank 40 along the recirculation line 36 to temporarily store the released dried CO2 at at least atmospheric pressure. Additionally, corresponding recirculation valves 42 are provided in the recirculation line 36 to control the recirculation of the CO2.

Claims

R.410913 - 12 - Claims 1. Method for operating a CO2 separation device (10) for separating CO2 from a supplied gas stream (14), in particular an air stream (14) from an environment, with at least one chamber (16) for receiving a CO2 separation agent (19) for a CO2 separation process, in particular a sorption process, and a CO2 release process, in particular a desorption process, characterized in that CO2 released by the release process is cooled and subsequently recirculated back into the chamber (16) to cool the CO2 separation agent (19) for the following CO2 separation process.

2. Method according to claim 1, characterized in that the released CO2 is cooled to substantially ambient temperature in order to cool the CO2 separation agent (19) to a defined temperature.

3. Method according to claim 1 or 2, characterized in that water present in the released CO2 is removed, in particular condensed, before recirculation.

4. Method according to one of the preceding claims, characterized in that the cooling of the CO2 and / or the removal of the water is carried out before or during a compression process of the released CO2, in particular by means of a cooler (34).

5. Method according to one of the preceding claims, characterized in that the released CO2 is temporarily stored in an intermediate storage container (40) at least at atmospheric pressure.

6. Method according to one of the preceding claims, characterized in that the released CO2 is processed by means of a R.410913 - 13 - The fluid is recirculated into the chamber (16) via a recirculation line (36) and a recirculation blower (38).

7. CO2 separation device (10) for separating CO2 from a supplied gas stream (14), in particular an air stream (14) from an environment, comprising at least one chamber (16) for receiving a CO2 separation agent (19) for a CO2 separation process, in particular a sorption process, and a CO2 release process, in particular a desorption process, characterized in that the CO2 separation device (10) is configured to cool CO2 released by the release process and subsequently recirculate it back into the chamber (16) to cool the CO2 separation agent (19) for the following CO2 separation process.

8. CO2 separation device (10) according to claim 7, characterized by a cooler (34) upstream of a pump unit (32) of the CO2 separation device (10) for cooling the CO2 and / or for removing water from the released CO2.

9. CO2 separation device (10) according to claim 7 or 8 characterized by an intermediate storage (40) for intermediate storage of the released CO2 at at least atmospheric pressure.

10. CO2 separation device (10) according to one of claims 7 to 9, characterized by a recirculation line (36) and a recirculation blower (18) for recirculating the released CO2 into the chamber (16).

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