Device for reducing a proportion of a predetermined gas in a gas mixture to be treated

Abstract

The present invention relates to a device (10) for reducing a proportion of a predetermined gas in a gas mixture to be treated, in particular for reducing the proportion of CO2 in air intended for generating compressed air, the device comprising: an inlet line (12) for the gas mixture to be treated, wherein the inlet line (12) branches in a first branching region (14) to form a main line (16) and a branch line (18), and the main line (16) and the branch line (18) merge in a second branching region (20) to form an outlet line (22) for treated gas mixture; and a gas treatment device (24) which is assigned to the branch line (18) and which is designed to at least partially separate off the predetermined gas from the gas mixture. According to the invention, the device (10) also comprises: an adjustable aperture unit (34) which is assigned to the main line (16) and which is configured to adjust an effective flow cross section of the main line (16); and at least one sensor unit (26a, 26b) which is configured to determine the proportion of the predetermined gas in the gas mixture for treatment or in the treated gas mixture and to output corresponding sensor data. The invention also relates to a system formed from such a device (10) and a compressor unit (100), and to a method for operating such a device (10).

Description

[0001] Device for reducing a proportion of a predetermined gas in a gas mixture to be treated

[0002] Description

[0003] The present invention relates to a device for reducing a proportion of a predetermined gas in a gas mixture to be treated, in particular for reducing the proportion of CO2 in air intended for compressed air generation, comprising an inlet line for the gas mixture to be treated, wherein in the flow direction of the gas mixture the inlet line branches into a main line and a branch line in a first branching region and the main line and the branch line combine in a second branching region to form an outlet line for treated gas mixture, and a gas treatment device assigned to the branch line, which is designed to at least partially separate the predetermined gas from the gas mixture.Furthermore, the present invention relates to a system for generating compressed air with controlled or regulated CO2 content, comprising such a device, and a method for operating such a device.

[0004] Although the following will focus in particular on the example of reducing the proportion of CO2 in breathing air in connection with the generation of compressed air, it is nevertheless understood that the device according to the invention can in principle also be suitable for reducing proportions of other predetermined gases in various types of gas mixtures to be treated.

[0005] In connection with the production and filling of compressed air and in particular breathing air for various applications, it is known that a specified CO2 content in the air to be filled must not be exceeded. For example, in Europe the corresponding limit is set at 500 ppm (DIN EN 12021 and NATO standard Stannag 1458) and in the USA at 1,000 ppm (US standard NFPA1989 or CGA-G7.1). However, it should be noted that depending on local conditions and possibly also weather conditions, cases can arise in which these values ​​are exceeded in the ambient air. This means that the ambient air must first be treated to reduce the CO2 content before it can be filled as compressed air for corresponding applications.

[0006] To ensure that the above-mentioned limit values ​​are not exceeded in such treated air, for example,

[0007] DE 100 471 37 B4 discloses passing the air intended for compressed air generation through a gas treatment device in which the CO2 is chemically bound and thus separated from the air. In particular, so-called "soothing lime" is used here. This consists of a mixture of calcium hydroxide and sodium hydroxide and, when used correctly, can separate essentially all of the CO2 from the air stream passing through it. However, this soaking lime is used up over time and must therefore be replaced as soon as it is saturated with CO2 after a certain period of time. For this purpose, replaceable cartridges are generally used. These contain the soaking lime and can be inserted into the corresponding line of the device so that the gas stream to be treated can flow through it.

[0008] In the aforementioned DE 100 471 37 B4, the air stream to be treated is divided according to its volume, and two-thirds of this is passed through the soda lime for treatment, while one-third of the total air volume remains untreated. The untreated and treated gas mixture portions are then combined and mixed so that, assuming complete CO2 capture in the gas treatment device, the CO2 concentration is reduced to one-third after passing through the corresponding device. In other devices also known from the prior art, alternative fixed ratios between the treated air stream and the untreated air stream have been used; however, these ratios were always determined prior to commissioning of the device in question based on the desired operating parameters and geometric properties.

[0009] In this case, the permissible service life of the gas treatment equipment used was generally determined in tests and implemented in productive operation based on various safety factors. Accordingly, the chemicals used to treat the gas mixture, in particular the aforementioned soda lime, were regularly replaced based on a service life table. However, it has been shown that such equipment is inefficient in that, due to the specified safety margins, a higher than necessary proportion of the gas mixture to be treated is generally passed through the gas treatment equipment in order to ensure that the specified limit values ​​for the predetermined gas in the treated gas mixture are never exceeded.This limits the possible service life of the gas treatment facility before the chemicals used must be replaced, which is expected to result in increased downtime and increased costs. Furthermore, additional safety margins must be provided regarding the potential saturation of the chemicals used, so that replacement will generally be carried out in a state in which they are not yet fully saturated, which will also lead to increased downtime and increased operating costs for the facility.

[0010] Accordingly, both the costs for the chemicals used in corresponding gas treatment facilities, which are not yet fully saturated when they are replaced, and the costs for avoidable downtimes represent disadvantages of the known prior art for which there is still potential for optimization. To achieve this object and to eliminate the aforementioned disadvantages of the prior art, the invention proposes to further provide, in a generic device, an adjustable orifice unit assigned to the main line, which is configured to adapt an effective flow cross-section of the main line, and at least one sensor unit configured to determine the proportion of the predetermined gas in the gas mixture to be treated or the treated gas mixture and to output corresponding sensor data.

[0011] Accordingly, in the device according to the invention, by means of a continuous operation of the at least one sensor unit or at least an operation thereof synchronized in a reasonable manner with relatively short measuring intervals, it can first be determined to what extent the gas mixture to be treated is to be subjected to the corresponding treatment, or whether such a treatment is necessary at all in order to be able to achieve predetermined limit values ​​or otherwise determined maximum proportions of the corresponding predetermined gas in the treated gas mixture.

[0012] On this basis, the orifice unit acting as a throttle can then be adjusted to determine the ratio in which the gas mixture flows through the main line and the branch line, whereby a higher effective flow cross-section of the main line will directly lead to a higher flow rate of the main line compared to the branch line and only the part of the gas mixture flowing through the branch line is subjected to a treatment to reduce the predetermined gas.

[0013] It should be noted that the provision of the gas treatment device in the branch line will in any case result in increased flow resistance for the gas mixture portion to be treated. On this basis, the corresponding flow cross-sections of the main line and the branch line can be adjusted in a suitable manner in order to achieve a desired range of flow conditions between the main line and the branch line by adjusting the orifice unit. Corresponding designs of the device according to the invention can be made based on previous calculations based on known geometric and fluidic properties and / or based on measurements on prototypes.Accordingly, in particular by a suitable design of the aperture unit, taking into account the properties of the gas treatment device used, it can be ensured that expected ranges of proportions of the predetermined gas in the gas mixture to be treated can be covered in the desired manner while adhering to the corresponding limit values.

[0014] In any case, a treated gas mixture can be drawn off from the outlet line of the device according to the invention, which mixture comprises, on the one hand, the treated portion flowing through the gas treatment device and, on the other hand, an untreated portion flowing through the main line, provided that the corresponding orifice unit is not completely closed, which, however, is not preferred anyway for reasons discussed below.

[0015] Furthermore, it should be noted that various forms of orifice units are conceivable for use in a device according to the invention, in particular two-part orifices with various forms of circular matrices with cutouts and associated perforated covers, which can produce a different effective flow cross-section of the main line by a relative rotation against each other.

[0016] In one embodiment, the orifice unit can be assigned an actuator that can be operated to adjust the orifice unit. The actuator can be arranged, for example, outside the flow path of the gas mixture. In the previously mentioned example of two-part, mutually rotatable orifices, such an actuator can be designed, for example, as a stepper motor, which can effect a predetermined angular relationship between the matrix with cutouts and the associated perforated cover to set a desired effective flow cross-section. In this case, it is particularly suitable to integrate the corresponding actuator in a blind pipe socket attached to the main line or on an outer side of the main line and to mechanically couple it to the rotatable orifice component so that it does not contribute to turbulence in the gas mixture in the main line.However, alternative variants are of course also conceivable, in which a corresponding actuator could, for example, be located on a hub of a rotatable aperture component or could be fixed to a fixed aperture component and would be supplied with electrical power from the outside.

[0017] Furthermore, the device according to the invention can comprise a control unit that is operatively coupled to the at least one sensor unit and configured to control the actuator of the orifice unit to adjust the flow cross-section of the main line based on the detected proportion of the predetermined gas in the gas mixture to be treated and / or in the treated gas mixture. In this way, automated operation of the device according to the invention can be achieved, i.e., the device can independently adjust the orifice unit and thus divide the gas flow between the main line and the branch line based on the data determined by the at least one sensor unit.

[0018] Alternatively or additionally, the device according to the invention can comprise a display unit which is configured to output the proportion of the predetermined gas in the gas mixture to be treated and / or in the treated gas mixture, as determined by the at least one sensor unit. The corresponding data can be prepared in a manner suitable for a human operator that is easy to read, for example, represented graphically or similarly. In this way, in embodiments of the device according to the invention in which no automatic adjustment of the aperture unit is provided, a human operator can be informed of the proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture in order to make a corresponding adjustment of the aperture unit.On the other hand, in embodiments in which automatic adjustment of the aperture unit is provided, such a display unit may also be advantageous to enable a human operator to monitor the correct functioning of the device during operation of the device. A corresponding display unit may either be physically integrated into the device or be formed by a portable device that exchanges data with the device, for example, a portable computer equipped with suitable software and a data connection to the device, or a smartphone.

[0019] Furthermore, it may be advantageous in the device according to the invention to provide at least two of the aforementioned sensor units, of which at least one is arranged upstream of the gas treatment device and at least one is arranged downstream of the gas treatment device. With regard to the type of sensor unit, this can also be tailored to the corresponding gas mixture and, in particular, to the predetermined gas. For example, in the case of CO2 in air, it is known to determine the corresponding proportion using infrared sensors, which are readily available on the market.

[0020] In any case, the mentioned integration of at least two sensor units can not only be used to verify the plausibility and improve the recorded measured values, but it can also ensure the effect and functioning of the device by recording, on the one hand, the proportion of the predetermined gas in the gas mixture still to be treated and, on the other hand, the proportion of the predetermined gas in the gas mixture already treated and, on this basis, verifying the correct functioning of the device.

[0021] Furthermore, in any case, by arranging at least one sensor unit downstream of the gas treatment device at this point, it can be ensured that, on the one hand, predetermined limit or target values ​​are adhered to, whereby, with the additional provision of a further sensor unit upstream of the gas treatment device, the effect of the gas treatment device can be directly monitored and, for example, if a diminishing effect is detected, an end of the service life thereof can be determined or, for example, leaks in the lines of the device can be detected.Thus, the respective processing performance of the gas treatment device can be monitored on the basis of several correspondingly recorded sensor values, whereby a human operator or an automated control system can determine in which area of ​​the life cycle the gas treatment device and in particular a corresponding cartridge is currently located.

[0022] The orifice plate unit of the device according to the invention can in particular be designed such that it is adjustable, preferably continuously adjustable, between a minimally open and a maximally open state, wherein in the minimally open state a minimum effective flow cross-section of the main line remains, which is greater than 0. By thus preventing the orifice plate unit from ever being completely closed, it is ensured that a certain proportion of the gas mixture always flows through the main line, thereby simultaneously preventing excessive back pressure from building up in the branch line and the gas treatment device, which could damage them.

[0023] It has been shown that the minimally open state of the orifice unit can correspond to a state of the device in which between 30% and 50%, preferably approximately 40%, of the gas mixture flows through the main line. Consequently, in the example mentioned, between 50% and 70%, preferably approximately 60%, of the gas mixture would flow through the gas treatment device, whereby the actual gas flow through the two lines depends on various geometric parameters of these lines as well as the physical and chemical properties of the treatment device. However, the corresponding flow proportions can be calculated based on known properties of the aforementioned components or determined experimentally, so that appropriate adjustment of the orifice unit before commissioning is easily possible.Similarly, when the orifice unit is fully open, between 90% and 95%, preferably about 92%, of the gas mixture can flow through the main line and the remaining gas mixture can flow through the gas treatment device, since even when the orifice unit is fully open, a residual portion of the gas mixture will still flow through the branch line, which is always open.

[0024] With regard to the gas treatment device, this can, for example, comprise a container filled with soda lime and arranged to be passed through by the gas mixture flowing through the branch line, wherein the container is preferably assigned to the branch line as a whole and can be replaced. As already indicated above, such replaceable containers are also referred to as cartridges and are often superior, particularly in terms of their handling, to variants in which the chemicals are exchanged as bulk material. In this case, the chemicals used must always be adapted to the gas mixture to be treated and in particular to the predetermined gas. For the application of CO2 to be removed from air, the aforementioned soda lime can be used.

[0025] Furthermore, the device according to the invention can comprise at least one humidity sensor, which is configured to determine the moisture content of the gas mixture and which is preferably arranged upstream of the gas treatment device. In this way, drying out of the gas treatment device due to excessively long continuous operation of the device can be avoided, which in some cases has limited the daily operating time of corresponding prior art devices in previously known systems. The corresponding data from the at least one humidity sensor can be forwarded to a control unit in a similar manner to the data from the sensor unit for determining the proportion of the predetermined gas in the gas mixture or can be displayed on a display for a human operator.It is also possible to provide a humidification device upstream of the gas treatment device, which is designed to humidify the gas mixture to be treated, preferably in a manner controlled on the basis of the data supplied by the at least one humidity sensor.

[0026] Furthermore, it should be noted that the device according to the invention may further comprise a storage unit and / or a communication unit configured to store data output by the at least one sensor unit or to transmit it to an external storage device. In this way, historical profiles of the function of the device according to the invention can be recorded, which can be stored, for example, on a cloud server and can accordingly be accessed in the future, for example, for maintenance or security purposes.

[0027] In addition, the device according to the invention can further comprise a safety device which is designed to initiate at least one predetermined measure if a permissible proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture is exceeded as detected by the at least one sensor unit, wherein, for example, a warning can be issued to a human operator or even a shutdown of the device or a higher-level system can be considered if the predetermined limit values ​​are no longer complied with.

[0028] Furthermore, the present invention relates to a system for generating compressed air with a controlled or regulated CO2 content, comprising a compressor unit and a device of the type just described upstream of the compressor unit. By means of such a system, breathing air can therefore be filled, in which compliance with predetermined limit values ​​can be monitored in real time and, at the same time, optimized consumption of the gas treatment device of the device according to the invention can be ensured.

[0029] According to yet another aspect, the present invention relates to a method for operating a device of the type just described, comprising the steps of introducing a gas mixture to be treated into the inlet line, permanently determining the proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture, and adjusting the effective flow cross-section of the main line by means of the orifice unit on the basis of the determined proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture.As already indicated above, the permanent determination of the proportion of the predetermined gas can also include a clocked determination with a suitable clock frequency of the corresponding sensor unit, which, however, is always carried out during the entire operation of the device and not only selectively to verify the functioning of the device for maintenance purposes or the like.

[0030] As already indicated, the gas mixture may be air and the predetermined gas CO2 and the aperture unit may be adjusted during the process such that the proportion of CO2 in the treated air is less than 1,000 ppm or less than 500 ppm.

[0031] Further features and advantages of the present invention will become more apparent from the following description of an embodiment thereof, when considered together with the accompanying figures. These show in detail:

[0032] Figure 1 is a cross-sectional view through a device according to the invention;

[0033] Figure 2 is a simplified isometric sectional view of a portion of the device shown in Figure 1; Figure 3 is a further enlarged cross-sectional view of a modified variant of the device shown in Figure 1;

[0034] Figures 4a to 4d show the aperture unit of the device of Figure 1 in four different opening states; and

[0035] Figure 5 shows an alternative variant of a diaphragm unit for the device of Figure 1.

[0036] Figure 1 shows, first of all, a device according to the invention for reducing the proportion of a predetermined gas in a gas mixture to be treated in a cross-sectional view and is generally designated by reference numeral 10. The device 10 can, for example, be provided to reduce the proportion of CO2 in air intended for compressed air generation. For this purpose and to form a system according to the invention, a compressor unit 100, indicated only schematically here, can be connected downstream of the device 10.

[0037] The device 10 comprises an inlet line 12 for the gas mixture to be treated, which is fed into the device at this point and flows to a first branching region 14, in which the inlet line 12 branches into a main line 16 and a branch line 18. Further downstream in the flow direction of the gas mixture flowing through the main line 16 and the branch line 18, a second branching region 20 is provided, in which the main line 16 and the branch line 18 rejoin, so that downstream of the second branching region 20, a single output 22 is present, which runs in the manner already mentioned to the downstream compressor unit 100 and carries a treated gas mixture thereto. The flow paths of the gas mixture are indicated in Figure 1 by corresponding dashed arrows.In the device 10 of Figure 1, the branch line 18 is assigned a gas treatment device 24, which comprises a replaceable cartridge 24a, i.e., a container filled with a chemical selected to separate the predetermined gas from the gas mixture. In one example, this can be soda lime, which acts to absorb CO2 essentially completely from the air until saturation and thus maximum absorption capacity is reached, necessitating replacement of the cartridge 24a.

[0038] Furthermore, Figure 1 indicates that the device 10 comprises two sensor units 26a and 26b, which are assigned to the inlet line 12 and the outlet line 22, respectively, and are each configured to determine the proportion of the predetermined gas in the gas mixture to be treated or the treated gas mixture and to output corresponding data to a control unit 28. Furthermore, a humidity sensor 32a and a humidification device 32b are assigned to the inlet line 12, wherein the humidity sensor 32a also supplies data to the control unit 28, and the humidification device 32b can be controlled for operation by the control unit 28.The control unit 28 is configured, on the one hand, to display the data supplied by the sensor units 26a and 26b on a display unit 28a, which may be provided on the device 10 or formed by a communicatively coupled remote device, and, on the other hand, to perform the adjustment of the flow components in the main line 16 and the branch line 18, as described in detail below. Furthermore, the control unit 28 is assigned a storage unit 28b and a communication unit 28c, which is configured to store the data output by the sensor units 26a, 26b or to transmit it to an external storage device (not shown), for example, a cloud server.

[0039] At this point, it should be noted that the humidification device 32b can also be arranged at a different position in the device 10 and, in particular, can be assigned to the branch line 18, i.e., it is then only intended to humidify the gas mixture that actually flows through the gas treatment device 24, while the gas mixture flowing through the main line 16 can remain dry. Such an arrangement of the humidification device 32b can be advantageous in that if the gas mixture exiting the device 10 needs to be dehumidified again before or in a downstream process step, for example, compression, the moisture input within the device 10 can already be reduced, thus simplifying the downstream dehumidification step.

[0040] In addition, the control unit 28 can act as a safety device in that it is further configured to initiate at least one predetermined measure, for example to open a discharge valve (not shown), to issue a warning to a human operator on the display device 28a and / or to deactivate the compressor unit 100, if a permissible proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture is exceeded as detected by at least one of the sensor units 26a, 26b.

[0041] Reference is now made to Figures 2 and 3, which each show an enlarged view of part of the device 10, and in particular the main line 16 and adjacent components. In Figure 2, it can be seen, first of all in a simplified view, that the main line 16 is assigned a diaphragm unit 34 which can be manually adjusted by a user and which limits the effective flow cross-section of the main line 16 and for this purpose comprises an operating element (not shown in detail), for example a pivoting lever accessible from the outside. This setting can be made in particular using the data output on the display device 28a, which can, for example, be displayed in such a way that the user is directly shown how to correctly operate or adjust the diaphragm unit at the appropriate time.In this way, the ratio of the mass fractions of the gas mixture entering through the inlet line 12 flowing through the main line 16 and the branch line 18 can be adjusted and adapted in order to achieve a desired proportion of the predetermined gas in the treated gas mixture exiting through the outlet line 22.

[0042] Figure 3 shows an enlarged cross-sectional view of an automatically driven orifice unit 34, which, however, corresponds to that of Figure 1 in terms of its basic mode of operation and a large part of its components. The orifice unit 34 is constructed in two parts and comprises two disks 36a and 36b which can be rotated relative to one another and which are each formed with cooperating openings such that the effective flow cross-section is varied by rotating the disks 36a and 36b relative to one another.An example of such interacting discs 36a and 36b is shown in Figures 4a to 4d in different relative angular orientations viewed in the direction of arrows IV in Figure 3, wherein it is clear that by rotating the discs 36a, 36b relative to one another, the resulting opening 36c can be adjusted between a minimum value and a maximum value, whereby the minimum value is, however, already greater than zero. Figure 4a corresponds to a maximally open state of the diaphragm unit 34, in which the second disc 36b is still completely covered and thus not visible. The other Figures 4b and 4c each correspond to increasingly closed states, and Figure 4d ultimately corresponds to a maximally closed state, in which, however, a central opening 36c still remains, since the second disc 36b is also cut out in its central region.

[0043] Furthermore, Figure 3 shows an actuator 38 embodied as an electric stepper motor, which can cause the second disc 36b to rotate relative to the first disc 36a in a precise and almost stepless manner and is arranged such that it always leaves the resulting opening 36c free. The actuator thus replaces the manual actuation mentioned above in connection with the variant from Figure 2; otherwise, however, the corresponding functions of the other components are essentially identical.Here, the actuator 38 is supplied with power via a line 38a in a manner controlled by the control unit 28, so that the adjustment of the effective flow cross-section can be carried out automatically by the control unit 28 on the basis of the data supplied by the sensor units 26a and 26b in order to achieve a desired limit value proportion of the predetermined gas in the treated gas mixture to be withdrawn through the outlet line 22.

[0044] Alternatively, however, variants of the present invention would also be conceivable in which the adjustment of the state of the aperture unit could be performed manually by an operator by providing corresponding actuating elements on the outside of the device 10, for example, for rotating the two discs 36a, 36b relative to each other. This adjustment could be performed by the operator based on values ​​displayed on the display device 28a indicating the proportion of the predetermined gas in the untreated and / or treated gas mixture.

[0045] Finally, reference is also made to Figure 5, which shows an alternative variant of a disc 36c with perforations, which could be used in the orifice unit 34 analogously to the discs 36a, 36b shown in Figures 4a to 4d. A corresponding second disc, coordinated with the disc 36c, could be formed in a similar manner, and again, the effective flow cross-section in the main line 16 could be adjusted by rotating the two discs relative to each other.

Claims

Claims 1 . Device (10) for reducing a proportion of a predetermined gas in a gas mixture to be treated, in particular for reducing the proportion of CO2 in air intended for compressed air production, comprising: - an inlet line (12) for the gas mixture to be treated, wherein the inlet line (12) branches into a main line (16) and a branch line (18) in a first branching region (14) and the main line (16) and the branch line (18) combine in a second branching region (20) to form an outlet line (22) for the treated gas mixture; and - a gas treatment device (24) associated with the branch line (18), which is designed to at least partially separate the predetermined gas from the gas mixture; characterized in that it further comprises: - an adjustable orifice unit (34) associated with the main line (16) which is designed to adjust an effective flow cross-section of the main line (16); and - at least one sensor unit (26a, 26b) which is designed to determine the proportion of the predetermined gas in the gas mixture to be treated or the treated gas mixture and to output corresponding sensor data.

2. Device (10) according to claim 1, wherein the aperture unit (34) is assigned an actuator (38) which can be operated to adjust the aperture unit (34).

3. Device (10) according to claim 1 or 2, further comprising a control unit (28) which is operatively coupled to the at least one sensor unit (26a, 26b) and configured to is to control the actuator (38) of the orifice unit (34) for adjusting the flow cross-section of the main line (16) on the basis of the detected proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture.

4. Device (10) according to one of the preceding claims, further comprising a display unit (28a) which is configured to output the proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture determined by the at least one sensor unit (26a, 26b).

5. Device (10) according to one of the preceding claims, comprising at least two sensor units (26a, 26b), of which at least one is arranged upstream of the gas treatment device (24) and at least one is arranged downstream of the gas treatment device (24).

6. Device (10) according to one of the preceding claims, wherein the aperture unit (34) is configured such that it is adjustable, preferably continuously adjustable, between a minimally open and a maximally open state, wherein in the minimally open state a minimum effective flow cross-section of the main line (16) remains which is greater than zero.

7. Device (10) according to the preceding claim, wherein the minimally open state of the aperture unit (34) corresponds to a state of the device (10) in which between 30 and 50%, preferably about 40%, of the gas mixture flows through the main line (16) and / or the maximally open state of the aperture unit (34) corresponds to a state of the device (10) in which between 90 and 95%, preferably about 92%, of the gas mixture flows through the main line (16).

8. Device (10) according to one of the preceding claims, wherein the gas treatment device (24) comprises a container (24a) which is filled with, in particular, soda lime and is arranged such that the gas mixture flowing through the branch line (18) passes through it, wherein the container (24a) is preferably assigned to the branch line (18) in an exchangeable manner as a whole.

9. Device (10) according to one of the preceding claims, further comprising at least one humidity sensor (32a) which is configured to determine a moisture content of the gas mixture and which is preferably arranged upstream of the gas treatment device (24).

10. Device (10) according to one of the preceding claims, further comprising a humidification device (32b) provided upstream of the gas treatment device (24), which is designed to humidify the gas mixture to be treated, preferably in a manner controlled on the basis of the data supplied by the at least one humidity sensor (32a).

11. Device (10) according to one of the preceding claims, further comprising a storage unit (28b) and / or a communication unit (28c) which is configured to store data output by the at least one sensor unit (26a, 26b) or to transmit it to an external storage device.

12. Device (10) according to one of the preceding claims, further comprising a safety device (28) which is designed to initiate at least one predetermined measure if a permissible proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture is exceeded as detected by the at least one sensor unit (26a, 26b).

13. System for generating compressed air with controlled or regulated CC content, comprising a compressor unit (100) and a device (10) upstream of the compressor unit (100) according to one of the preceding claims.

14. A method for operating a device (10) according to any one of claims 1 to 12, comprising the steps: - introducing a gas mixture to be treated into the inlet line (12); - permanently determining the proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture; and - adjusting the effective flow cross-section of the main line (16) by means of the orifice unit (34) on the basis of the determined proportion of the predetermined gas in the gas mixture to be treated and / or the treated gas mixture.

15. Method according to the preceding claim, wherein the gas mixture is air and the predetermined gas is CO2 and the aperture unit is adjusted such that the proportion of CO2 in the treated air is less than 1000 ppm or less than 500 ppm.

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