Method and apparatus for removing atmospheric oxygen from an adsorber material enriched with carbon dioxide

Abstract

The invention relates to a method for removing atmospheric oxygen from a granular adsorber material (1) enriched with carbon dioxide, in particular in a DAC system (100; 100a), wherein the atmospheric oxygen is displaced from the adsorber material (1) by a medium that displaces the atmospheric oxygen.

Description

[0001] R.415510

[0002] - 1 -

[0003] Description

[0004] Method and apparatus for removing atmospheric oxygen from a carbon dioxide-enriched adsorbent material

[0005] Technical field

[0006] The invention relates to a method for removing atmospheric oxygen from a granular adsorbent material enriched with carbon dioxide, particularly in a DAC plant, which enables the minimization of oxygen input into a desorption section and the minimization of carbon dioxide losses prior to desorption using simple, effective, and cost-efficient means. The invention further relates to a device for carrying out the method according to the invention.

[0007] State of the art

[0008] To limit the warming of the Earth's atmosphere, it is known to actively remove carbon dioxide from the ambient air in a first system using so-called "Direct Air Capture" (DAC) systems. This allows the carbon dioxide to be permanently bound in a second system, for example, by injecting it into geological cavities (source: https: / / de.wikipedia.org / wiki / Direct_Air_Capture). To remove the carbon dioxide from the air in the first system, it is also known to use a solid, granular adsorbent material such as zeolite or Lewatit® VP OC 1065. Furthermore, to enable a closed loop of the adsorbent material, i.e., reuse of the adsorbent material, it is also known from the prior art to remove the carbon dioxide-enriched adsorbent material in a desorption process by heating. It is important that, if necessary, the spaces between the R.415510

[0009] - 2 -

[0010] Atmospheric oxygen present in the adsorbent material is removed to improve the efficiency of the desorption process and to prevent oxygen-induced degradation of the adsorbent material. This is usually done by pumping with a vacuum system (US 10279 306 B2), or by using steam as an inert gas according to WO 2021 / 239748 A1, which discloses a method with the features of the preamble of the claim.

[0011] Disclosure of the invention

[0012] The inventive method for removing atmospheric oxygen from a carbon dioxide-enriched, granular adsorbent material with the features of claim 1 has the advantage that it enables, with relatively simple process engineering means, an almost complete removal of atmospheric oxygen from the carbon dioxide-enriched adsorbent material prior to desorption with high efficiency or little loss of carbon dioxide.

[0013] The invention is based on the idea of ​​using a liquid instead of the commonly used water vapor or inert gas or a vacuum system, which displaces the atmospheric oxygen located in the adsorber material, particularly in the cavities between the particles of the adsorber material.

[0014] In light of the above explanations, a method according to the invention for removing atmospheric oxygen from a granular adsorbent material enriched with carbon dioxide, having the features of claim 1, therefore has the feature that the adsorbent material is brought into operative contact with a medium that displaces the atmospheric oxygen from the adsorbent material, wherein a liquid is used as the medium.

[0015] Advantageous further developments of the inventive method for removing atmospheric oxygen from a granular adsorbent material enriched with carbon dioxide are listed in the dependent claims.

[0016] It is essential that the liquid used has low solubility for atmospheric oxygen and / or carbon dioxide. This allows for advantageous use of R.415510.

[0017] - 3 -

[0018] This method allows the liquid to be continuously circulated or repeatedly used to remove atmospheric oxygen from the adsorbent material. Furthermore, this ensures that the carbon dioxide is removed exclusively within the desorption unit, thus increasing efficiency. Such a process also makes it possible to potentially dispense with a (separate) airlock upstream of the desorption unit, as the introduction of dissolved atmospheric oxygen into the liquid is minimal. The liquid can be removed either in the airlock leading to the desorption chamber and / or in the desorption section in either liquid or gaseous form. In particular, after passing through a heat exchanger, the liquid can be reused for energy recovery by condensing it from the carbon dioxide product gas stream. Since the liquid has already been used, it may be...Once saturated with carbon dioxide, it does not absorb any further carbon dioxide upon being brought back into contact with the adsorbent material.

[0019] The liquids used are primarily water and / or ionic liquids, which dissolve little or no oxygen and can be easily separated from the carbon dioxide. Solubility of carbon dioxide in the liquid is generally acceptable, especially in continuous processes with separate adsorption and desorption units, because a continuous process will establish at least a locally constant equilibrium of the carbon dioxide concentration in the liquid, so that no carbon dioxide is lost in the overall process.

[0020] Regarding the technical implementation of the process, there are essentially two possibilities: On the one hand, the adsorbent material can be treated by the medium in the area of ​​a lock, with the continuously or batch-operated lock then conveying the adsorbent material into a desorption chamber or desorption unit. On the other hand, the adsorbent material can be treated by the liquid medium in a closed chamber, forming a combined adsorption and desorption chamber, so that no circulation or transport of the adsorbent material takes place. R.415510

[0021] - 4 -

[0022] The use of water as a liquid to displace atmospheric oxygen is particularly advantageous. The oxygen, along with the carbon dioxide, transitions into the gas phase and is thus present as water vapor in the carbon dioxide product gas stream. Recovery from a hot, carbon dioxide-containing product gas stream after desorption of the adsorbent material can therefore be easily achieved by condensing the water using a heat exchanger. This results in a particularly high efficiency due to the heat recovery through water condensation and thus a relatively low overall energy consumption. Furthermore, as explained above, no (further) dissolution of carbon dioxide occurs in the water, as it is already saturated. The solubility of oxygen in water is known to be very low.

[0023] The invention also includes a device for carrying out a method according to the invention as described so far, which is characterized by a lock device for the continuous or batch treatment of the adsorber material with the liquid and a desorption device connected to the lock device or alternatively by a closed chamber for treating the adsorber material with the liquid, wherein the chamber is designed as an adsorption and desorption chamber.

[0024] With regard to the constructive design of a lock or transport device between spatially separated adsorption and desorption, it is preferably designed as a rotary valve, as a double slide valve or as a zone of a tubular chain conveyor.

[0025] A particularly preferred design of the sluice gate includes at least one siphon. This design has the advantage that it may not require any moving parts for conveying the adsorbent material.

[0026] Further developing the previously made proposal, it is envisaged that at least one siphon is designed for the at least indirect introduction of the adsorbent material into a desorber. R.415510

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[0028] Finally, in a further advantageous embodiment of the aforementioned sluice device, it may be provided that a further siphon is provided for venting the adsorber material from the desorption device.

[0029] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings.

[0030] Brief description of the drawings

[0031] Fig. 1 and

[0032] Fig. 2 shows schematic representations of differently designed DAC systems with the essential components of the invention and

[0033] Fig. 3 shows the area of ​​a desorption device with two siphons for supplying and removing the adsorber material into and out of the desorption device, also in a schematic representation.

[0034] Embodiments of the invention

[0035] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0036] Figure 1 shows a highly simplified representation of the first DAC system 100 for removing carbon dioxide from ambient air UL, depicted only with the essential components necessary for understanding the invention. The DAC system 100 comprises an adsorption chamber 10 through which ambient air UL flows. This chamber binds the carbon dioxide present in the ambient air UL using a solid, particulate or granular adsorbent material 1, in particular Lewatit® VP OC 1065. The carbon dioxide-saturated adsorbent material 1 then passes via a first conveying section 12 into the area of ​​a continuously or batchwise R.415510

[0037] - 6 - operating lock device 14, which conveys the adsorber material 1 into a desorption device 16.

[0038] In the desorption device 16, as is known in the prior art, the carbon dioxide is removed from the saturated adsorber material 1 by means of high temperatures, in particular temperatures of more than 100°C, and is extracted from the desorption device 16 by means of a pumping device 18.

[0039] The hot product gas stream containing carbon dioxide, which, as explained below, also contains water vapor, is then fed to a heat exchanger 20. Here, in addition to energy recovery for the desorption unit 16, the condensed water is separated. This water is returned to the airlock unit 14 via a return line 22 and serves to remove atmospheric oxygen from the spaces between the particles of the adsorbent material 1. From the heat exchanger 20, the remaining carbon dioxide is conveyed via a discharge line 24 to a further application, in particular storage or emplacement.

[0040] In contrast, the adsorber material 1, now free of carbon dioxide, then passes through a second conveying section 26 (and possibly a second airlock device not shown) from the desorption chamber 16 and possibly further devices not shown in Fig. 1 back into the adsorption chamber 10.

[0041] As already explained, the water, as liquid F, serves to displace the adsorbent material 1, which typically contains atmospheric oxygen in the spaces between the particles of adsorbent material 1 in addition to carbon dioxide, before the adsorbent material 1 enters the area of ​​the desorption unit 16. This is achieved by pouring the adsorbent material 1, for example, into a volume filled with water or liquid F in the airlock unit 14, so that the atmospheric oxygen, which, like carbon dioxide, has only very low solubility in water, rises to the surface of the volume and is thus displaced from the spaces between the particles of adsorbent material 1 by the water. R.415510

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[0043] By means of a suitable design of the sluice device 14, which is designed, for example, in the form of a rotary valve, a double slide valve, or as a zone of a tubular chain conveyor, the adsorbent material 1 contained in the water, preferably with only a small amount of water, is conveyed into the desorption device 16. During the desorption process, the water evaporates due to the high temperatures and is conveyed as water vapor into the heat exchanger 20, where it condenses.

[0044] Figure 2 shows a DAC system 100a comprising a combined adsorption / desorption chamber 30. In the adsorption / desorption chamber 30, the adsorbent material 1 is alternately used to absorb carbon dioxide from the ambient air and, after enrichment with the carbon dioxide, desorbed to repeat the adsorption process. For this purpose, the adsorption / desorption chamber 30 is typically connected to a variety of other devices, not shown in Figure 2, which enable the necessary functions of supplying the ambient air and for desorption.

[0045] Essentially, before the desorption process begins, the adsorbent material 1 in the adsorption / desorption chamber 30 is flooded with liquid F (water) by means of a pump 32 to displace the atmospheric oxygen contained in the adsorbent material 1. This oxygen is then released, for example, to the environment via a valve 34. After the valve 34 is closed, the water or liquid F is removed by a pump 36 and fed into a storage tank 38, from which the pump 32 is also supplied with liquid F, so that the desorption process can then be started. Similar to the DAC system 100, after the desorption process in the adsorption / desorption chamber 30, the extracted product gas stream is passed through a heat exchanger (not shown) to recover the water or liquid F and return it to the adsorbent material 1 via the storage tank 38.

[0046] The lock assembly 14 shown in Fig. 1 can, as already explained, be designed in particular as a rotary valve, double slide valve or as a zone of a tubular chain conveyor. However, it is also possible that the lock assembly 14 is designed according to the illustration in R.415510.

[0047] - 8 -

[0048] Fig. 3 includes at least one siphon 40, which is arranged in the inlet area to a closed chamber 42 that is part of the desorption device 16. In addition, in the illustrated embodiment, a second siphon 44 is provided, which conveys desorbed adsorbent material 1 from a desorber 46 of the desorption device 16 through a passage in the chamber 42.

[0049] While a pressure pi prevails inside the chamber 42, the pressure outside the chamber 42 is p2, where the pressure p2 is greater than the pressure pi. This is preferably made possible by an evacuable chamber 42 (not shown).

[0050] The carbon dioxide-enriched adsorbent material 1 enters, for example, the siphon 40, which is filled with water (liquid F), via a funnel 47. Specifically, the adsorbent material 1 enters the chamber 42 via a curved outlet 48 that passes through a partition 50. Since the pressure pi in the chamber 42 is lower than the pressure p2, the water level WPi is higher than the water level WP2 outside the chamber 42. Furthermore, due to its lower density compared to water, the adsorbent material 1 rises within the chamber 42 in a shaft 52. Simultaneously, when the adsorbent material 1 is introduced into the water, the ambient air contained within the adsorbent material 1 is displaced by the water and rises, for example, in the form of air bubbles, along with the adsorbent material 1 in the shaft 52 and enters the chamber 42.From shaft 52, the adsorber material 1 is conveyed via a chute 54 by gravity into the desorber 46, where the carbon dioxide is removed from the adsorber material 1.

[0051] In the second siphon 44, which is connected to the desorber 46 and is also filled with water, a screw conveyor 56 is arranged as an example, which conveys the adsorber material 1 into an outer area 60 of the second siphon 42, from where it can be removed or transported further.

[0052] The DAC system 100, 100a described above can be adapted or modified in various ways without deviating from the inventive concept. It is also conceivable to use other liquids instead of water as liquid F. The only essential requirement is that these liquids exhibit low solubility for atmospheric oxygen and / or carbon dioxide.

Claims

R.415510 - 9 - Claims 1. Method for removing atmospheric oxygen from a carbon dioxide-enriched, granular adsorbent material (1), in particular in a DAC plant (100; 100a), in which the atmospheric oxygen is removed from the adsorbent material (1) by a medium displacing the atmospheric oxygen, characterized in that a liquid (F) is used as the medium.

2. Method according to claim 1, characterized in that the liquid (F) has a low solubility for atmospheric oxygen and / or carbon dioxide.

3. Method according to claim 1 or 2, characterized in that water and / or an ionic liquid (F) is used as the liquid (F).

4. Method according to one of claims 1 to 3, characterized in that the atmospheric oxygen is displaced from the adsorber material (1) in the area of ​​a sluice device (14) or a closed chamber (30).

5. Method according to claim 4, characterized in that the conveying of the adsorber material (1) in the area of ​​the airlock device (14) and the displacement of the atmospheric oxygen from the adsorber material (1) by the liquid (F) takes place continuously or in batches, or that the displacement of the atmospheric oxygen from the adsorber material (1) by the liquid (F) takes place in the closed R.415510 - 10 - Chamber (30) after a desorption process and before an adsorption process.

6. Method according to one of claims 3 to 5, characterized in that water is used as the liquid (F) which is obtained by recovery from a hot product gas stream containing carbon dioxide after desorption of the adsorber material (1) by means of a heat exchanger (20).

7. Device for carrying out a method according to claims 1 to 6, comprising a lock device (14) for the continuous or batch treatment of the adsorber material (1) with the liquid (F) and a desorption device (16) adjoining the lock device (14), or comprising a closed chamber (30) for the treatment of the adsorber material (1) by the liquid (F), wherein the chamber (30) is designed to be operable as a combined adsorption and desorption chamber.

8. Device according to claim 7, characterized in that the lock device (14) is designed as a rotary valve, double slide valve or as a zone of a tubular chain conveyor.

9. Device according to claim 7, characterized in that the lock device (14) has at least one siphon (40, 44).

10. Device according to claim 9, characterized in that the at least one siphon (40) is designed at least indirectly for introducing the adsorber material (1) into a desorber (46).

11. Device according to claim 10, characterized in that, R.415510 - 11 - that a further siphon (44) is provided for the discharge of the adsorber material (1) from the desorption device (16).

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