DEVICE FOR EXTRACTING VAPOR AND / OR AEROSOLS RISE DURING A galvanizing process in a galvanizing or anodizing tank

Abstract

According to the invention, a device 1 is provided for extracting vapors and / or aerosols rising during an electroplating process in an electroplating or anodizing tank 50. The device comprises a longitudinally oriented supply air unit 10 and an exhaust air unit 20, which can be attached to opposite sides of an electroplating or anodizing tank 50. The supply air unit 10 is designed to discharge jets of supply air parallel to the surface of a process fluid 30, which is contained in the electroplating or anodizing tank 50 during the intended use of the device 1. The exhaust air unit 20 is designed to extract the supply air jets enriched with vapors and / or aerosols. According to the invention, the supply air unit 10 has a plurality of supply air openings 12 and at least one pressure chamber 14, which is fluidly connected to the plurality of supply air openings 12.The invention further provides that at least one of the air inlet openings 12 is fluidly connected to the at least one pressure chamber 14 via an elongated channel 12c, and that the channel 12c has a length L in the direction of flow which is at least 3 times the hydraulic diameter of a cross-sectional area, viewed perpendicular to the direction of flow, which is at least one air inlet opening 12, whereby the supply air jet enriched with vapors and / or aerosols can be captured by the exhaust air unit 20.

Description

AREA OF INVENTION

[0001] The present invention relates to a device for extracting vapors and / or aerosols rising during a galvanizing process in an electroplating tank or anodizing tank. BACKGROUND OF THE INVENTION

[0002] An electroplating or anodizing tank is typically a large, rectangular container made of a corrosion-resistant material, such as plastic or stainless steel. It is filled with a process fluid required for the electroplating process. The tank walls are often smooth for easy cleaning. The size and shape of the electroplating tank can vary depending on the application and the workpieces being coated.

[0003] Electroplating or anodizing tanks contain electrodes immersed in the process fluid. These electrodes are crucial to the process, as they conduct the electric current required for the deposition of metal onto the workpieces being electroplated or for the anodic oxidation of aluminum workpieces. Often, fixtures or racks are also used to hold the workpieces in the correct position during electroplating or anodic oxidation.

[0004] Electroplating often produces fumes, aerosols, or gaseous substances that can be harmful to health. Therefore, effective extraction is necessary to keep these substances away from work areas and separate them from the environment. Extraction is thus a crucial component of the overall system, ensuring health protection, occupational safety, and environmental protection in electroplating.

[0005] The capture of hazardous substances and the determination of the required air volumes are crucial for complying with legally mandated air limit values. At the point where hazardous substances are to be captured and extracted, the extraction air must maintain a minimum air velocity. This minimum air velocity must be greater than the velocity of the rising hazardous substances. Furthermore, any cross-currents in the ambient air can influence the required minimum air velocity.

[0006] In practice, various extraction systems are used. For example, an exhaust hood can be positioned above the pool to directly capture rising vapors and / or aerosols. This hood is either permanently installed or movable, allowing it to be positioned above the pool as needed.

[0007] In the case of perimeter extraction 1*, as exemplified in Fig.As shown in Figure 1, extraction openings 22*, provided in one or two exhaust air units 20a*, 20b*, are located at one edge (one-sided edge extraction) or both edges (two-sided edge extraction) of the basin 50* directly above the process liquid. Edge extraction is particularly effective at capturing aerosols and gases directly at the source before they escape into the ambient air. However, the suction effect decreases significantly with increasing distance between the extraction opening in the exhaust air unit and the hazardous substance location. Therefore, a high exhaust air volume flow rate is required to compensate.

[0008] There are also so-called push-pull systems, which represent a special type of edge extraction used in electroplating. These systems are designed to capture rising fumes more effectively compared to single- or double-sided edge extraction. Fresh air is blown across the surface of the tank via a nozzle or air duct on one side. This air is typically blown in at a relatively low velocity, creating an "air curtain" above the tank. A suction bar or duct is located on the opposite side of the tank. The extraction system should be adjusted to efficiently capture the entire airflow from the push side, along with the vapors and aerosols it carries. The push-pull system is mounted at the edges of the electroplating or anodizing tank, with air intake and extraction along the long sides.The system is mounted using stable, corrosion-resistant brackets or supports, which are attached either directly to the tank frame or via additional support structures. With push-pull systems, there is a risk that the airflow will be reflected back during loading and unloading of workpieces from the electrolyte bath, preventing the distribution and capture of contaminants. Similarly, the extraction volume flow rate must be very high to prevent the escape of harmful gases, which is why push-pull systems typically require a great deal of energy.

[0009] Since the fumes in electroplating are often highly corrosive, the materials used for the hood or perimeter extraction system must be corrosion-resistant. The extracted fumes and gases are conveyed through a network of ducts. High-performance fans ensure that the air is extracted continuously and with a sufficient volume flow. These ducts lead to a central exhaust system where the air is filtered and purified before being released into the environment.

[0010] To ensure the functionality and safety of the extraction system, sensors are often installed to monitor airflow and pollutant concentrations. If the extraction system malfunctions, warning signals are issued or the system is automatically shut down to prevent hazardous situations.

[0011] The extraction system must be designed to capture all potentially hazardous substances without disrupting the production process. However, excessive airflow can agitate the liquids in the tank and impair the efficiency of the electroplating process.

[0012] One object of the present invention is to minimize, and in some cases even eliminate, the disadvantages prevalent in the prior art. In particular, one object of the invention is to improve the extraction of vapors and / or aerosols rising during an electroplating process in an electroplating or anodizing tank, while simultaneously reducing the energy required for this purpose.

[0013] These and other problems of the invention are solved by claim 1. Optional or preferred features of the invention are specified in the dependent claims. SUMMARY OF THE INVENTION

[0014] According to the invention, a device is provided for extracting vapors and / or aerosols rising during an electroplating process in an electroplating or anodizing tank. The device according to the invention comprises an air supply unit having a longitudinal axis and an exhaust air unit, which can be attached to opposite sides of an electroplating or anodizing tank. The air supply unit is designed to discharge jets of supply air parallel to the surface of a process fluid contained in the electroplating or anodizing tank during the intended use of the device, and the exhaust air unit is designed to extract the supply air jets enriched with vapors and / or aerosols. According to the invention, the air supply unit has a plurality of air supply openings for discharging the supply air jets and at least one pressure chamber that is fluidly connected to the plurality of air supply openings.The invention further provides that at least one of the air inlet openings is fluidly connected to the at least one pressure chamber via an elongated channel, and that the channel has a length L in the direction of flow that is at least 3 times the hydraulic diameter of a cross-sectional area, viewed perpendicular to the direction of flow, which is at least one air inlet opening, whereby the supply air jet enriched with vapors and / or aerosols can be captured by the exhaust air unit.

[0015] The device according to the invention is fundamentally suitable for extracting any rising vapors and / or aerosols that arise both during the metallic coating of workpieces in an electroplating tank and during the anodic oxidation of aluminum components in an anodizing tank. Because the supply air flows through a channel with a length L, which is at least three times the hydraulic diameter of a cross-sectional area perpendicular to the flow direction of the corresponding supply air opening, before exiting the supply air opening, supply air jets are emitted from the supply air unit above the process fluid. These jets are thus given a direction that is significantly more pronounced than that of air jets that only have to traverse a shorter channel.The supply air jets are already highly directional at the moment they leave the supply air openings, ensuring they are positioned as close as possible to the process fluid. This results in particularly efficient capture of the rising vapors and / or aerosols. Furthermore, this leads to energy savings, as the exhaust air unit can be operated with a lower volume flow without compromising the safety of the extraction system.

[0016] Unlike conventional push-pull systems, which only roughly direct free jets towards the exhaust unit, the invention delivers directed supply air jets from the supply unit. A free jet is a jet that spreads freely into the surrounding space without being directed or focused in a specific direction by external forces or limitations. A typical example of an undirected free jet is the airflow delivered into a room by a fan or blower. Undirected free jets are ideal for applications where a wide distribution of a medium is desired, such as for general room ventilation or cooling of large areas. However, they are less suitable when precise control or concentration of the jet is required.In contrast, a directed beam is a beam that is specifically focused and directed in a particular direction by mechanical devices such as nozzles, pipes or channels.

[0017] The air supply duct according to the invention is not limited to a cylindrical duct whose cross-sectional shape is circular perpendicular to the flow direction. In order to compare different ducts with different cross-sectional shapes fluid-dynamically, the so-called hydraulic diameter is used. The term "hydraulic diameter" is known to those skilled in this field and represents a calculated value that indicates the diameter of a flow duct with any cross-section which, at the same length and mean flow velocity, exhibits the same pressure loss as a flow pipe with a circular cross-section and the same diameter.

[0018] According to a preferred embodiment, the channel has a length L in the flow direction that is at least 3 to 11 times the hydraulic diameter of the cross-sectional area, viewed perpendicular to the flow direction, which includes at least one air inlet. Such a channel imparts an even more pronounced directed movement to the supply air, which has an even more advantageous effect on the capture of rising vapors and / or aerosols and therefore leads to further energy savings on the part of the exhaust air unit.

[0019] It is advantageous if all air inlets of the multiple air inlets are fluidly connected to the at least one pressure chamber via an elongated channel, and if each channel has a length L in the direction of flow that is at least three times the hydraulic diameter of a cross-sectional area, viewed perpendicular to the direction of flow, of the corresponding air inlet. This achieves very efficient extraction along the entire longitudinal side of the electroplating or anodizing tank.

[0020] It is even more advantageous if each channel has a length L in the direction of flow that is at least 4 to 11 times the hydraulic diameter of the cross-sectional area, viewed perpendicular to the direction of flow, of the associated air inlet opening.

[0021] Preferably, each channel has the same length L, so that the rising vapors and / or aerosols can be captured as homogeneously as possible along the longitudinal side of the electroplating or anodizing tank.

[0022] According to a further preferred embodiment, a cross-sectional area of ​​the at least one air inlet opening, viewed perpendicular to the flow direction, preferably of all air inlets, lies within a range of 1 mm. 2 up to 5 mm 2 . A jet exit aperture with such a small cross-section allows for a high jet exit velocity despite a low jet volume flow, resulting in a greater range of the jet (up to the opposite extraction opening).

[0023] Preferably, the outlet end of at least one channel, or preferably all channels, facing the electroplating or anodizing tank, is tapered. This tapering of the outlet end accelerates the air in the channel uniformly, resulting in reduced flow resistance and further enhancing the effect of the directed movement of the supply air.

[0024] It is advantageous if the numerous air inlets along the longitudinal axis of the air inlet unit are arranged such that, during normal use of the device, all air inlets are equidistant from the surface of the process liquid. This creates a directed and focused air curtain above the process liquid, consisting of numerous individual jets that combine to form a single jet. This curtain maintains a constant distance from the process liquid along the longitudinal side of the basin and exhibits a strong directional movement component towards the exhaust unit.

[0025] Furthermore, it is advantageous if the numerous air supply openings have a circular, round, oval, rectangular, or polygonal shape. In particular, circular and round air supply openings simplify manufacturing and contribute to the cost-effectiveness of the air supply unit.

[0026] If the multiple air inlets are preferably connected fluidically to only one pressure chamber, the manufacturing costs of the air supply unit are reduced. Furthermore, a pressure source that generates the air jets only needs to be fluidically connected to one pressure chamber of the air supply unit.

[0027] According to a preferred embodiment, the pressure chamber is fluidly connected to an electric fan. Due to the inventive design of the supply air unit, a supply air volume flow rate that can be generated by an electric fan is sufficient. A supply air volume flow rate generated by an electric fan is significantly more energy-efficient compared to a volume flow rate that is typically generated by a compressed air system permanently installed in a building, resulting in further energy savings.

[0028] Preferably, the air inlets of the multiple air inlets are evenly spaced along the longitudinal axis of the air inlet unit. This results in a more homogeneous extraction of vapors and / or aerosols along the longitudinal side of the basin.

[0029] It is advantageous if the distance between two adjacent air inlets along the longitudinal axis of the air supply unit is such that the air jets emerging from the multiple air inlets merge into a single flat jet that covers the entire surface of the process fluid contained in the electroplating or anodizing tank. This further optimizes the capture and subsequent extraction of the air jets contaminated with vapors and / or aerosols by the exhaust unit.

[0030] The invention will now be described purely by way of example with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a perspective view of a conventional electroplating or anodizing tank with attached double-sided edge suction; Fig.Figure 2 shows a perspective view of an electroplating or anodizing tank with an attached air supply unit and exhaust unit according to a preferred embodiment of the invention; Fig. Figure 3 shows a perspective view of a partial aspect of an air supply unit according to a preferred embodiment of the invention; Fig. Figure 4 shows, purely as an example, the velocity profile of the extracted exhaust air streams and the corresponding exhaust air volume flows in a conventional electroplating or anodizing tank with edge extraction on both sides; and Fig. 5 shows in comparison to the Fig. 4 the velocity profiles of the supply and exhaust air flows and the associated exhaust air volume flow in an electroplating or anodizing tank with supply air unit and exhaust air unit according to a preferred embodiment of the invention. DETAILED DESCRIPTION OF AN EXAMPLE EXECUTION

[0031] In the drawings, identical or series-associated reference numerals indicate identical or functionally equivalent structural components of the device according to the invention.

[0032] In principle, the device according to the invention is suitable both for extracting vapors and / or aerosols that arise during the metallic coating of workpieces in an electroplating tank, and for extracting vapors and / or aerosols that arise during the anodic oxidation of aluminium components in an anodizing tank.

[0033] The shape of the electroplating or anodizing tank plays a rather subordinate role in the invention. The invention is therefore applicable to tanks with different geometries and dimensions.

[0034] Fig.Figure 2 shows a perspective view of an electroplating or anodizing tank 50 with an attached air supply unit 10 and exhaust unit 20 according to a preferred embodiment of the invention. The tank 50, which comprises four side walls 51, is open only at its top. The side walls 51 of the tank 50 thus define a partially open interior space 52.

[0035] The air supply unit 10 and the exhaust air unit 20 are preferably detachably attached to opposite longitudinal sides with the edges of the side walls 51 of the basin 50.

[0036] The supply air unit 10 and / or the exhaust air unit 20 are preferably cuboid in shape. The cuboid housing of the supply air unit 10 and / or the exhaust air unit 20 each has a wall facing the interior 52 of the basin 50, in which a plurality of supply air openings 12 are provided in the supply air unit 10 and a plurality of exhaust air openings 22 are provided in the exhaust air unit 20. The supply air openings 12 are preferably fluidically connected to a channel 14 arranged inside the cuboid housing of the supply air unit 10, while the exhaust air openings 22 are preferably fluidly connected to a channel arranged inside the cuboid housing of the exhaust air unit 20.

[0037] In Fig.Figure 2 shows only the plurality of exhaust openings 22 of the exhaust unit 20, which are preferably slot-shaped. However, the shape of the exhaust openings 22 can also be circular, round, oval, or another shape. The exhaust unit 20, preferably the channel arranged inside the cuboid housing of the exhaust unit 20, is fluidly connected to a vacuum source, such as a pump, to generate a vacuum inside or in the area of ​​the exhaust openings 22 of the exhaust unit 20, which causes any vapors and / or aerosols that arise during the electroplating process to be extracted by the exhaust unit 20. The supply air unit 10, preferably the channel 14 arranged inside the cuboid housing of the supply air unit 10 ( Fig.3) is fluidly connected to an overpressure source 40, which ensures that air can be blown out of the supply air unit 10 in the form of supply air jets. The overpressure source 40 is preferably an electric fan ( Fig. 5), or even more preferably a radial compressor.

[0038] Fig.Figure 3 shows an exemplary embodiment of the air inlet openings 12. A plurality of air inlet openings 12 are provided in the air inlet unit 10, which are preferably arranged along the longitudinal side of the basin 50 and thus preferably evenly spaced relative to one another in the longitudinal direction of the air inlet unit 10. Furthermore, the air inlet openings 12 are preferably arranged at the same distance from the surface of the process fluid 30 within the basin 50 during intended use. The distance between two adjacent air inlet openings 12 along the longitudinal axis of the air inlet unit 10 is preferably such that the air jets exiting the plurality of air inlet openings 12 merge into a single directed and focused flat jet that covers the entire surface of the process fluid 30 contained in the electroplating or anodizing basin 50.

[0039] Each air inlet 12 has an inlet end 12a and an outlet end 12b. The inlet end 12a and the outlet end 12b are fluidically connected via an elongated channel 12c. The channel 12c has a length L. The in Fig. The side wall 11 of the supply air unit 10 shown in section 3 represents the internally arranged and in Fig. 2 non-visible inner wall facing the interior of the basin 52 in Fig. 2 shown supply air unit 10.

[0040] As in Fig. As indicated by dashed lines 3, the longitudinal axis of the channel 12c does not have to run perpendicular to those end faces of the wall 11 where the outlet end 12b and the inlet end 12a are provided, but can also extend at an angle to these end faces.

[0041] According to the invention, the channel length L is at least 3 times, preferably at least 4 to 11 times, the hydraulic diameter of a cross-sectional area, viewed perpendicular to the flow direction, of the corresponding air inlet 12, preferably the cross-sectional area of ​​the outlet end 12b of the air inlet 12. This ensures that the air inlet jets are given a direction that is significantly more pronounced than that of air jets that only have to traverse a shorter channel. This reduces the opening angle of the air inlet jets spreading over the process fluid. In other words, the air inlet jets are already so strongly directional at the moment they leave the air inlet 12 that they lie as close as possible to the process fluid, resulting in particularly efficient capture of the rising vapors and / or aerosols.This also leads to energy savings, as the exhaust air unit 20 can be operated with a lower volume flow without compromising the safety of the extraction.

[0042] Since the air supply duct 12c according to the invention is not limited to a cylindrical duct whose cross-sectional shape is circular perpendicular to the flow direction, different ducts 12c with different cross-sectional shapes can only be compared fluid-dynamically with the aid of the so-called hydraulic diameter. The term "hydraulic diameter" is known to those skilled in this field and represents a calculated value that indicates the diameter of a flow channel with any cross-section which, at the same length and the same mean flow velocity, has the same pressure loss as a flow pipe with a circular cross-section and the same diameter.

[0043] The cross-sectional area of ​​the air inlet opening 12, in particular of the outlet end 12b, viewed perpendicular to the flow direction, preferably of all air inlet openings 12b, lies in a range of 1 mm² 2 up to 5 mm 2 .

[0044] The inlet end 12a of the air inlet opening 12 is equipped with a pressure chamber 14 ( Fig. 5) Fluidly connected. Preferably, all inlet ends 12a of the supply air openings 12 are fluidly connected to only one pressure chamber 14. It is also conceivable that each channel 12c is fluidly connected to the overpressure source 40 via a hose (not shown). In this case, the hose represents the pressure chamber 14.

[0045] In the Fig.In the example shown in Figure 3, the inlet end 12a is preferably provided with a chamfer 13 which preferably has an angle of 45° to the longitudinal axis of the channel 12c. This angle can also be less than or greater than 45°. Preferably, the outlet end 12b is tapered at least by one, and preferably by all, of the supply air openings 12, whereby the supply air flowing through the channel 12c to the outlet end 12b is further accelerated at the outlet end 12b.

[0046] The Fig. 4 and the Fig. Figure 5 shows an exemplary experimental comparison of conventional bilateral perimeter suction ( Fig. 4) and the active flow guidance with directed discharge of the supply air jets from the supply air unit 10 towards the exhaust air unit 20 according to the invention ( Fig. 5).

[0047] Given a given size of the electroplating or anodizing tank (50*, 50) and a given electroplating process, an exhaust air volume flow of 1250 m³ / h is required. 3 / h within the exhaust air unit 20a*, 20b*, 20 is required to achieve the legally prescribed minimum air velocity of the extracted air volume, so with double-sided perimeter extraction 20a*, 20b* the total exhaust air volume flow is 2500 m³ 3 / h ( Fig. 4), while the exhaust air volume flow in the exhaust air unit 20 according to the invention continues to be 1250 m³ 3 / h is ( Fig. 5) The supply air jets in Fig. 5 are generated using an electric fan or radial compressor 40.

[0048] The Fig. 4 and the Fig. Figure 5 also shows the velocity profiles of the vapors and / or aerosols extracted by the exhaust air units 20a*, 20b*, 20. Fig.4 The speed decreases sharply with increasing distance to the exhaust air unit 20a*, 20b*, while in Fig. 5 the supply air has a relatively high velocity immediately after being blown out of the supply air unit 10, which then decreases towards the center of the basin and then increases again due to the suction effect of the exhaust air unit 20.

[0049] The following exemplary energy-saving potential can result from the active or directed flow guidance according to the invention: Boundary conditions:

[0050] Extraction - Old fan: 0.00125 kWh / m 3 - Modern fan: 0.0005 kWh / m 3

[0051] blow-off - Radial compressor: 0.01 kWh / m 3 - Electric fan (small): 0.0012 kWh / m 3 Conventional pelvic aspiration Basal suction with active flow guidance Ventilator alt:0,00125 kWh / m 3 × 2.500 m 3 / h = 3.125 W ⇨ Old fan: 0.00125 kWh / m² 3 × 1,250 m 3 / h = 1,560 W+ centrifugal compressor: 0.01 Wh / m 3 × 15 m 3 / h = 150 WΣ = 1,710 W -> 45% savings potential Ventilator modern:0,0005 kWh / m 3 × 2.500 m 3 / h = 1.250 W ⇨ Modern fan: 0.0005 kWh / m 3 × 1,250 m 3 / h = 625 W + Small electric fan: 0.0012 Wh / m 3 × 15 m 3 / h = 18 WΣ = 645 W -> 48% savings potential

[0052] The advantages of the active or directed flow guidance according to the invention can be described as follows: The airflow directed from the supply air unit efficiently captures vapors and / or aerosols across the entire width of the pool surface, preventing them from spreading uncontrollably throughout the room. This minimizes the impact on the work environment and improves employee safety.

[0053] Compared to traditional perimeter extraction systems, which require large volumes of air to capture vapors and / or aerosols, the invention enables more precise and targeted extraction. This results in a lower exhaust air volume flow, thus reducing energy consumption.

[0054] Because the invention causes the airflow above the basin surface to move in a directed manner, the risk of the process fluid in the basin being disturbed by strong air currents is minimized. This ensures a more stable electroplating or anodic oxidation quality.

[0055] The device according to the invention is generally less bulky and does not impair access to the basin. It can be easily integrated into existing systems and adapted to different basin sizes and processes.

Claims

Device (1) for extracting vapors and / or aerosols rising during an electroplating process in an electroplating or anodizing tank (50), comprising an air supply unit (10) having a longitudinal axis and an exhaust air unit (20) which can be attached to opposite sides of an electroplating or anodizing tank (50), wherein the air supply unit (10) is designed to discharge jets of supply air parallel to the surface of a process liquid (30) which is contained in the electroplating or anodizing tank (50) during the intended use of the device (1), and the exhaust air unit (20) is designed to extract the jets of supply air enriched with vapors and / or aerosols, and wherein the air supply unit (10) has a plurality of air supply openings (12) for discharging the jets of supply air and at least one pressure chamber (14) which is fluidly connected to the plurality of air supply openings (12), characterized in thatthat at least one of the air inlet openings (12) is fluidly connected to the at least one pressure chamber (14) via an elongated channel (12c), and that the channel (12c) has a length L in the direction of flow that is at least 3 times the hydraulic diameter of a cross-sectional area, viewed perpendicular to the direction of flow, which is at least one air inlet opening (12), whereby the supply air jet enriched with vapors and / or aerosols can be captured by the exhaust air unit (20). Device (1) according to claim 1, wherein the channel (12c) has a length L in the direction of flow which is at least 3 times to 11 times the hydraulic diameter of the cross-sectional area, viewed perpendicular to the direction of flow, which has at least one air inlet opening (12). Device (1) according to claim 1 or 2, wherein all air inlet openings (12) of the plurality of air inlet openings (12) are fluidly connected to the at least one pressure chamber (14) via an elongated channel (12c), and that each channel (12c) has a length L in the direction of flow which is at least 3 times the hydraulic diameter of a cross-sectional area, viewed perpendicular to the direction of flow, of the associated air inlet opening (12). Device (1) according to claim 3, wherein each channel (12c) has a length L in the direction of flow which is at least 4 to 11 times the hydraulic diameter of the cross-sectional area, viewed perpendicular to the direction of flow, of the associated air inlet opening (12). Device (1) according to claim 3 or 4, wherein each channel (12c) has the same length L. Device (1) according to one of the preceding claims, wherein a cross-sectional area of ​​the at least one air inlet opening (12), viewed perpendicular to the flow direction, preferably of all air inlets openings (12), lies in a range of 1 mm2 to 5 mm2. Device (1) according to one of the preceding claims, wherein an outlet end (12b) of the at least one channel (12c), preferably of all channels (12c), facing the electroplating or anodizing tank (50), is tapered. Device (1) according to one of the preceding claims, wherein the plurality of air inlet openings (12) is arranged along the longitudinal axis in the air inlet unit (10) such that, during the intended use of the device (1), all air inlet openings (12) of the plurality of air inlet openings (12) have the same distance to the process liquid surface (30). Device (1) according to one of the preceding claims, wherein the plurality of air inlet openings (12) have a circular, round, oval, rectangular or polygonal shape. Device (1) according to one of the preceding claims, wherein the plurality of air inlet openings (12) is fluidly connected to only one pressure chamber (14). Device (1) according to one of the preceding claims, wherein the pressure chamber (14) is fluidly connected to an electric fan (40). Device (1) according to one of the preceding claims, wherein the air inlet openings (12) of the plurality of air inlet openings (12) are spaced evenly apart from each other along the longitudinal axis of the air inlet unit (10). Device (1) according to claim 12, wherein the distance between two air supply openings (12) adjacent along the longitudinal axis of the air supply unit (10) is such that the air supply jets exiting from the plurality of air supply openings (12) combine to form a single flat jet which covers the entire surface of the process fluid (30) contained in the electroplating or anodizing tank.

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