Co2 adsorption system with a co2 adsorption device for separating co2 (carbon dioxide) and an alkaline fuel cell

Abstract

The invention relates to a CO2 adsorption system (10) with a CO2 adsorption device (12) for separating CO2 from a supplied air stream (14) by means of an adsorption-desorption process, and with a fuel cell (22), in particular an alkaline fuel cell (22) or PEM fuel cell for electrochemical energy conversion, wherein the CO2 adsorption device (12) and the fuel cell (22) can be or are fluidically coupled to one another by means of a first coupling unit, in particular an air line, and can be or are thermally coupled to one another by means of a second coupling unit, in particular a temperature control link, for heating the CO2 adsorption device (12).

Description

[0001] Description

[0002] title

[0003] CO2 adsorption system with a CO2 adsorption device for separating CO2 (carbon dioxide) and an alkaline fuel cell

[0004] State of the art

[0005] The invention relates to a CO2 adsorption system comprising a CO2 adsorption device for separating CO2 from a supplied air stream by means of an adsorption-desorption process, and a fuel cell, in particular an alkaline fuel cell or PEM fuel cell, for electrochemical energy conversion. The invention further relates to a method for operating such a CO2 adsorption system, a method for separating CO2 from a supplied air stream, and the use of a fuel cell, in particular an alkaline fuel cell or PEM fuel cell, for heating a CO2 adsorption device for separating CO2 from a supplied air stream by means of an adsorption-desorption process.

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

[0007] WO 2014 / 170184 A1, WO 2015 / 185434 A1, and WO 2020 / 212146 A1 disclose such a DAC system in which, in a first step, CO2 from the air is temporarily bound to an adsorber medium by conveying it via a fan (adsorption), so that in a second step, after the unit has been sealed against the environment, the CO2 can be removed again from the adsorber medium (desorption). As is familiar to a person skilled in the art, adsorption is carried out under different physical conditions than desorption. This means that adsorption takes place, for example, at 25°C, 1013 mbar, and a relative humidity of 50%RH, and desorbed at 80°C and 200 mbar, which is why, among other things, the adsorbent must be heated for desorption. In addition to PEM fuel cells (acidic membrane fuel cells), alkaline membrane fuel cells are also a possible future technology for converting hydrogen into electricity.Especially in alkaline membrane fuel cells, the supplied air should be as free from CO2 as possible, since CO2 can react with the charge carriers (OH-) to form insoluble carbonates.

[0008] Disclosure of the invention

[0009] The present invention relates to a CO2 adsorption system with

[0010] - a CO2 adsorption device for separating CO2 from a supplied air stream by means of an adsorption-desorption process and

[0011] - a fuel cell, in particular an alkaline fuel cell or PEM fuel cell for electrochemical energy conversion, wherein the CO2 adsorption device and the fuel cell

[0012] - for electrochemical energy conversion by means of a first coupling unit, in particular an air line, fluidically and

[0013] - for heating the CO2 adsorption device by means of a second coupling unit, in particular a temperature control line, which can be or are thermally coupled to one another.

[0014] The present invention further relates to a method for operating a CO2 adsorption system, in particular according to one of the preceding claims, with

[0015] - a CO2 adsorption device for separating CO2 from a supplied air stream by means of an adsorption-desorption process and

[0016] - a fuel cell, in particular an alkaline fuel cell or PEM fuel cell for electrochemical energy conversion, wherein the CO2 adsorption device and the fuel cell

[0017] - for electrochemical energy conversion by means of a first coupling unit, in particular an air line, fluidically and

[0018] - for heating the CO2 adsorption device, they are thermally coupled to one another by means of a second coupling unit, in particular a temperature control line.

[0019] The present invention also relates to a method for separating CO2 from a supplied air stream, wherein a CO2-reduced air stream from a CO2 adsorption device is supplied to a fuel cell, in particular an alkaline fuel cell or PEM fuel cell for electrochemical energy conversion, and waste heat generated in the fuel cell is supplied to the CO2 adsorption device for heating an adsorbent arranged therein.

[0020] The present invention further relates to the use of a fuel cell, in particular an alkaline fuel cell or PEM fuel cell, for heating, in particular for supplying energy / power to a CO2 adsorption device for separating CO2 from a supplied air stream by means of an adsorption-desorption process.

[0021] The CO2 adsorption device is designed or configured to separate CO2 from a supplied air stream by means of an adsorption-desorption process, i.e., a cyclically performed or implemented adsorption-desorption process. The basic functionality of the CO2 adsorption device or of the cyclically performed or implemented adsorption-desorption process can, for example, be analogous to WO 2020 / 212146 A1 mentioned above. The CO2 adsorption device is preferably designed to be stationary.

[0022] In the context of the present invention, the term “separation” includes a separation, for example the capture of CO2 (carbon dioxide) from the air.

[0023] Within the scope of the present invention, the term "supply" or "supplied" primarily encompasses an actively conducted or initiated, and thus technically controlled or regulated, supply of the air flow by means of a blower unit or fan unit. However, the term "supply" or "supplied" can also encompass a passively conducted 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, for example, naturally.

[0024] The fuel cell is preferably an alkaline fuel cell or an alkaline membrane fuel cell, or an acidic fuel cell or PEM fuel cell. The fuel cell is preferably stationary. Accordingly, the entire CO2 adsorption system is preferably stationary.

[0025] The CO2 adsorption system according to the invention offers the advantage that through the intelligent fluidic and thermal coupling or

[0026] By connecting / interconnecting a CO2 adsorption device to a fuel cell, the supply air for the fuel cell is freed of harmful CO2, i.e., "purified air" can be provided, enabling optimized electrochemical energy conversion. Conversely, the waste heat from the fuel cell can be used to operate the CO2 adsorption device (desorption of CO2). This creates an energy-efficient, resource-saving CO2 adsorption system.

[0027] The CO2 adsorption device and the fuel cell can be or are coupled fluidically and thermally.

[0028] In the context of the present invention, a fluidic coupling is understood to mean a fluidic connection / connection, wherein the fluid, in particular air, is delivered or directed from the CO2 adsorption device to the fuel cell for electrochemical energy conversion. Accordingly, the fluid or the air / atmospheric oxygen is "reacted" in the fuel cell, releasing energy. The fluidic coupling is achieved by means of a first coupling unit, which is designed, in particular, as an air line.

[0029] In the context of the present invention, a thermal coupling is understood to mean a thermal connection / connection, wherein heat, in particular by means of a temperature control medium, is transferred from the fuel cell to the CO2 adsorption device to heat the CO2 adsorption device. The thermal coupling is achieved by means of a second coupling unit, different from the first, which is designed in particular as a temperature control line. Consequently, for example, the temperature control medium can circulate in a closed circuit between the fuel cell and the CO2 adsorption device to heat the CO2 adsorption device as needed.In other words, this means that the fluidic and thermal coupling are each realized via separate coupling units, even if, from a physical point of view, the fluidic coupling always also involves a thermal coupling, which, however, does not serve to heat the CO2 adsorption device.

[0030] Advantageously, the CO2 adsorption device comprises at least one first adsorption-desorption chamber and at least one second adsorption-desorption chamber, which, in particular by means of a valve unit, are each coupled or can be coupled to the fuel cell either fluidically by means of the first coupling unit or thermally by means of the second coupling unit. The CO2 adsorption system preferably comprises a control unit which is configured to control the valve unit for fluidic and thermal coupling depending on an operating state of the CO2 adsorption device, in particular to control the valve unit in such a way that

[0031] - in a first operating state, the at least one first adsorption-desorption chamber is only fluidic and the at least one second adsorption-desorption chamber is only thermal, and

[0032] - in a second operating state, the at least one first adsorption-desorption chamber is only thermally coupled to the fuel cell and the at least one second adsorption-desorption chamber is only fluidically coupled to the fuel cell.

[0033] Consequently, the CO2-reduced air flow and the waste heat are supplied to the CO2 adsorption device depending on an operating state, wherein the CO2 adsorption device in particular comprises at least one first adsorption-desorption chamber and at least one second adsorption-desorption chamber, and

[0034] - in the first operating state, the CO2-reduced air flow from the at least one first adsorption-desorption chamber of the fuel cell and the waste heat are fed to the at least one second adsorption-desorption chamber, and

[0035] - in the second operating state, the CO2-reduced air flow from the at least one second adsorption-desorption chamber of the fuel cell and the waste heat are supplied to the at least one first adsorption-desorption chamber.

[0036] Thus, the valve unit for fluidic and thermal coupling can be controlled by means of the control unit depending on the operating state of the CO2 adsorption device, in particular such that

[0037] - in the first operating state, the at least one first adsorption-desorption chamber is only fluidic and the at least one second adsorption-desorption chamber is only thermal, and

[0038] - in the second operating state, the at least one first adsorption-desorption chamber is only thermally coupled to the fuel cell and the at least one second adsorption-desorption chamber is only fluidically coupled to the fuel cell.

[0039] The valve unit can comprise a plurality of, in particular controllable, valves. The valves can be arranged in the air line and the temperature control line to provide the optional coupling.

[0040] This advantageously allows several adsorption-desorption chambers to be operated in parallel during the adsorption-desorption process, since

[0041] - the adsorption-desorption chamber or group of adsorption-desorption chambers, which is currently undergoing the adsorption process, is or will be fluidically coupled to the fuel cell and thus supplied with the fuel “purified air”, while

[0042] - the other adsorption-desorption chamber or group of adsorption-desorption chambers, which undergoes the desorption process in parallel, is or will be thermally coupled to the fuel cell and is heated by it.

[0043] Advantageously, with regard to the fluidic coupling, a CO2-reduced air stream emerging from the CO2 adsorption device, in particular the adsorption-desorption chambers, can be fed to the fuel cell for electrochemical energy conversion. Preferably, an outlet channel for discharging the CO2-reduced air stream from the CO2 adsorption device, in particular the adsorption-desorption chambers, is fluidly connectable or connected to an air supply line of the fuel cell via the air line.

[0044] In other words, the outlet channel of the CO2 adsorption device or the outlet channels of the adsorption-desorption chambers, which serve to discharge the CO2-reduced air flow, are each fluidly connectable or connected by means of an air line to the air supply line of the fuel cell, which serves to supply the air or oxygen. In this case, a valve of the valve unit, in particular a controllable valve, can be arranged in each air line of the adsorption-desorption chambers.

[0045] It is further advantageous if, with regard to the thermal coupling, waste heat generated in the fuel cell can be supplied to the CO2 adsorption device, in particular to the adsorption-desorption chambers, for heating an adsorbent arranged therein(s). For the waste heat supply, a heating circuit of the CO2 adsorption device, in particular of the adsorption-desorption chambers, is preferably thermally connected or connectable to a cooling circuit of the fuel cell by means of the temperature control line.

[0046] In other words, the heating circuit of the CO2 adsorption device or the heating circuits of the adsorption-desorption chambers, which serve to heat the adsorbent during the desorption process, can be or are connected thermally, and optionally also fluidically, to the cooling circuit of the fuel cell, which serves to dissipate the waste heat, by means of a respective temperature control line. A valve, in particular a controllable valve of the valve unit, can be arranged in each temperature control line of the adsorption-desorption chambers. Bypass valves can understandably be used to change the thermal coupling between the adsorption-desorption chambers or to temporarily decouple the cooling circuit of the fuel cell from them.

[0047] Furthermore, it is advantageous if the power generated by the fuel cell can be supplied to the CO2 adsorption device via a power transmission unit, in particular a power line, in particular for operating at least one of the following units of the CO2 adsorption device: blower unit, valve unit, pump unit, steam generator, electric heating unit, control unit, sensor unit. This makes it possible to provide an energy- or electricity-independent CO2 adsorption system.

[0048] In other words, the CO2 adsorption device receives the required power for individual units or for all units from the fuel cell via a power transmission unit, particularly a power line. The units that are powered by electricity can be, for example:

[0049] - Blower unit for supplying the air flow;

[0050] - Valve unit for fluidic and thermal coupling;

[0051] - Pump unit for providing overpressure and / or negative pressure for the desorption process;

[0052] - Steam generator to provide steam for the desorption process;

[0053] - electric heating unit for additional heating of the adsorbent for the adsorption-desorption process;

[0054] - Control unit for controlling and / or regulating the adsorption-desorption process;

[0055] - Sensor unit for the adsorption-desorption process.

[0056] The blower unit can have a variety of fans.

[0057] The valve unit can have further controllable valves to close the adsorption-desorption chamber for the desorption process. The valve unit can have an inlet valve which is arranged in an inlet channel for the sucked-in air flow and is designed to close the inlet channel and to isolate the adsorption-desorption chamber upstream. The valve unit can further have an outlet valve which is arranged in an outlet channel for the CO2-reduced air flow and is designed to close the outlet channel and to isolate the adsorption-desorption chamber downstream. The valve unit can also have a CO2 valve which is arranged in a CO2 outlet channel and is designed to open the CO2 outlet channel in order to specifically discharge the adsorbed, i.e. bound / filtered and desorbed, i.e. released, CO2 from the adsorption-desorption chamber.The control unit can be designed to be connected to other control units and / or a central control unit of the CO2 adsorption system or a higher-level system by means of radio transmission such as Wi-Fi, Bluetooth, near-field communication, etc.

[0058] Advantageously, a hydrogen tank is also provided, which is or can be fluidly connected to a hydrogen supply line of the fuel cell to provide the hydrogen for the fuel cell. This allows for a completely self-sufficient CO2 adsorption system to be provided, to which only the air to be purified needs to be supplied.

[0059] Furthermore, a CO2 pressure storage unit may be provided to collect and store the CO2 released during the desorption process.

[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-

[0063] adsorption system in a first operating state; and

[0064] Fig. 2 shows the CO2 adsorption system according to the invention from Fig. 1 in a second operating state.

[0065] In Fig. 1 and Fig. 2 a CO2 adsorption system according to the invention is shown, which in its entirety is provided with the reference number 10.

[0066] Here, the CO2 adsorption system 10 is shown in Fig. 1 in a first operating state and in Fig. 2 in a second operating state, which are explained in more detail below, wherein for reasons of illustration only the “active” lines or streams are shown.

[0067] The CO2 adsorption system 10 comprises a CO2 adsorption device 12 for separating CO2 from a supplied air stream 14 by means of an adsorption-desorption process. The CO2 adsorption device 12 comprises a first adsorption-desorption chamber 16 and a second adsorption-desorption chamber 18, each of which contains an adsorbent 20.

[0068] The CO2 adsorption system 10 further comprises a fuel cell 22 for electrochemical energy conversion. The fuel cell 22 is configured as an alkaline membrane fuel cell.

[0069] According to the invention, the CO2 adsorption device 12 or the adsorption-desorption chamber 16, 18 and the alkaline membrane fuel cell 22 can be or are coupled to one another fluidically for electrochemical energy conversion by means of a first coupling unit (not shown), which is designed as an air line. In this case, a CO2-reduced air stream 24 emerging from the CO2 adsorption device 12 or the adsorption-desorption chambers 16, 18 can be fed to the alkaline membrane fuel cell 22 for electrochemical energy conversion, wherein an outlet channel 26 for discharging the CO2-reduced air stream 24 from the CO2 adsorption device 12 or the adsorption-desorption chambers 16, 18 can be or is connected fluidically by means of the air line to an air supply line 28 of the alkaline membrane fuel cell 22.

[0070] On the other hand, according to the invention, the CO2 adsorption device 12 or the adsorption-desorption chamber 16, 18 and the alkaline membrane fuel cell 22 can be or are thermally coupled to one another by means of a second coupling unit (not shown) which is designed as a temperature control line, in addition to heating the CO2 adsorption device 12 or the adsorption-desorption chambers 16, 18. In this case, the waste heat 30 generated in the alkaline membrane fuel cell 22 can be supplied to the CO2 adsorption device 12 or the adsorption-desorption chambers 16, 18 for heating the adsorbent 20, wherein for the waste heat supply, a heating circuit (not shown) of the CO2 adsorption device 12 or the adsorption-desorption chambers 16, 18 can be or is thermally connected by means of the temperature control line to a cooling circuit (not shown) of the alkaline membrane fuel cell 22.The CO2 adsorption system 10 also has a valve unit (not shown) by means of which the adsorption-desorption chambers 16, 18 can be or are coupled, optionally fluidically or thermally, to the alkaline membrane fuel cell 22. The CO2 adsorption system 10 also has a control unit (not shown) configured to control the valve unit for fluidic and thermal coupling depending on the operating state of the CO2 adsorption device 12 in such a way that.

[0071] - according to Fig. 1 in the first operating state, the first adsorption-desorption chamber 16 only fluidically and the second adsorption-desorption chamber 18 only thermally, and

[0072] - according to Fig. 2, in the second operating state, the first adsorption-desorption chamber 16 is only thermally coupled or connected to the alkaline membrane fuel cell 22 and the second adsorption-desorption chamber 18 is only fluidically coupled or connected.

[0073] For energy-autonomous operation of the CO2 adsorption system 10, the power 32 generated by the alkaline membrane fuel cell 22 can be at least partially supplied to the CO2 adsorption device 12 by means of a power transmission unit (not shown) designed as a power cable. This allows units (not shown) of the CO2 adsorption device 12, such as a blower unit, a valve unit, a pump unit, a steam generator, an electric heating unit, the control unit, or a sensor unit, to be operated.

[0074] On the other hand, the CO2 adsorption system 10 further comprises a hydrogen tank (not shown) which is fluidly connectable or connected to a hydrogen supply line 34 of the alkaline membrane fuel cell 22 in order to provide the hydrogen 36 and thus a completely self-sufficient CO2 adsorption system 10 to which only the air 14 to be purified needs to be supplied.

[0075] 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. CO2 adsorption system (10) with - a CO2 adsorption device (12) for separating CO2 from a supplied air stream (14) by means of an adsorption-desorption process and - a fuel cell (22), in particular an alkaline fuel cell (22) or PEM fuel cell for electrochemical energy conversion, wherein the CO2 adsorption device (12) and the fuel cell (22) - for electrochemical energy conversion by means of a first coupling unit, in particular an air line, fluidically and - for heating the CO2 adsorption device (12) by means of a second coupling unit, in particular a temperature control line, can be or are thermally coupled to one another.

2. CO2 adsorption system (10) according to claim 1, characterized in that the CO2 adsorption device (12) has at least one first adsorption-desorption chamber (16) and at least one second adsorption-desorption chamber (18), which can be coupled or are coupled to the fuel cell (22), in particular by means of a valve unit, either fluidically by means of the first coupling unit or thermally by means of the second coupling unit.

3. CO2 adsorption system (10) according to claim 2, characterized by a control unit which is designed to control the valve unit for fluidic and thermal coupling depending on an operating state of the CO2 adsorption device (12), in particular to control the valve unit in such a way that - in a first operating state, the at least one first adsorption-desorption chamber (16) is only fluidically and the at least one second adsorption-desorption chamber (18) is only thermally, and - in a second operating state, the at least one first adsorption-desorption chamber (16) is only thermally coupled to the fuel cell (22) and the at least one second adsorption-desorption chamber (18) is only fluidically coupled to the fuel cell (22).

4. CO2 adsorption system (10) according to one of the preceding claims, characterized in that with regard to the fluidic coupling, a CO2-reduced air flow (14) emerging from the CO2 adsorption device (12), in particular the adsorption-desorption chambers (16, 18), can be fed to the fuel cell (22) for electrochemical energy conversion.

5. CO2 adsorption system (10) according to claim 4, characterized in that for the air supply, an outlet channel (26) for discharging the CO2-reduced air flow (24) from the CO2 adsorption device (12), in particular the adsorption-desorption chambers (16, 18), is or can be fluidly connected by means of the air line to an air supply line (28) of the fuel cell (22).

6. CO2 adsorption system (10) according to one of the preceding claims, characterized in that waste heat (30) generated in the fuel cell (22) with respect to the thermal coupling can be supplied to the CO2 adsorption device (12), in particular to the adsorption-desorption chambers (16, 18) for heating an adsorbent (20) arranged in the latter.

7. CO2 adsorption system (10) according to claim 6, characterized in that for the waste heat supply, a heating circuit of the CO2 adsorption device (12), in particular of the adsorption-desorption chambers (16, 18), can be or is thermally connected to a cooling circuit of the fuel cell (22) by means of the temperature control line.

8. CO2 adsorption system (10) according to one of the preceding claims, characterized in that current (32) generated by the fuel cell (22) can be supplied to the CO2 adsorption device (12) by means of a current transmission unit, in particular for operating at least one of the following units of the CO2 adsorption device (12): blower unit, valve unit, pump unit, water vapor generator, electric heating unit, control unit, sensor unit.

9. CO2 adsorption system (10) according to one of the preceding claims, characterized by a hydrogen tank which is fluidly connectable or connected to a hydrogen supply line (34) of the fuel cell (22) in order to provide hydrogen (36) for the fuel cell (22).

10. A method for operating a CO2 adsorption system (10), in particular according to one of the preceding claims, with - a CO2 adsorption device (12) for separating CO2 from a supplied air stream (14) by means of an adsorption-desorption process and - a fuel cell (22), in particular an alkaline fuel cell (22) or PEM fuel cell for electrochemical energy conversion, wherein the CO2 adsorption device (12) and the fuel cell (22) - for electrochemical energy conversion by means of a first coupling unit, in particular an air line, fluidically and - for heating the CO2 adsorption device (12) are thermally coupled to one another by means of a second coupling unit, in particular a temperature control line.

11. Method according to claim 10, characterized in that a valve unit for fluidic and thermal coupling is controlled by means of a control unit depending on an operating state of the CO2 adsorption device (12), in particular the CO2 adsorption device (12) has at least one first adsorption-desorption chamber (16) and at least one second adsorption-desorption chamber (18), wherein the valve unit is controlled in such a way that - in a first operating state, the at least one first adsorption-desorption chamber (16) is only fluidically and the at least one second adsorption-desorption chamber (18) is only thermally, and - in a second operating state, the at least one first adsorption-desorption chamber (16) is coupled only thermally and the at least one second adsorption-desorption chamber (18) is coupled only fluidically to the fuel cell (22).

12. A method for separating CO2 from a supplied air stream (14), wherein a CO2-reduced air stream (24) from a CO2 adsorption device (12) of a fuel cell (22), in particular an alkaline fuel cell (22) or PEM fuel cell for electrochemical energy conversion, and waste heat (30) generated in the fuel cell (22) are fed to the CO2 adsorption device (12) for heating an adsorbent (20) arranged therein.

13. The method according to claim 12, characterized in that the CO2-reduced air flow (24) and the waste heat (30) are supplied as a function of an operating state of the CO2 adsorption device (12), wherein in particular the CO2 adsorption device (12) has at least one first adsorption-desorption chamber (16) and at least one second adsorption-desorption chamber (18), and - in a first operating state, the CO2-reduced air flow (24) from the at least one first adsorption-desorption chamber (16) of the fuel cell (22) and the waste heat are supplied to the at least one second adsorption-desorption chamber (18), and - in a second operating state, the CO2-reduced air flow (24) from the at least one second adsorption-desorption chamber (18) of the fuel cell (22) and the waste heat are supplied to the at least one first adsorption-desorption chamber (16).

14. Use of a fuel cell (22), in particular an alkaline fuel cell (22) or PEM fuel cell for heating, in particular further for supplying energy to a CO2 adsorption device (12) for separating CO2 from a supplied air stream (14) by means of an adsorption-desorption process.

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