Device for extracting vapors and / or aerosols rising during an electroplating process in an electroplating or anodizing tank.

Abstract

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).

Description

FIELD OF THE INVENTION

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

[0002] An electroplating tank 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 to allow for easy cleaning. The size and shape of the electroplating tank can vary depending on the application and the workpieces to be coated.

[0003] A plating or anodizing tank contains electrodes immersed in the process fluid. These electrodes are crucial to the process because they conduct the electrical current required for the deposition of metal on the workpieces being electroplated or for the anodic oxidation of aluminum workpieces. Holders or racks are often also provided to hold the workpieces being treated in the correct position during the electroplating or anodic oxidation process.

[0004] Electroplating often produces vapors, aerosols, or gaseous substances that can be harmful to health. Effective extraction is therefore necessary to keep these substances away from the work areas and to separate them so they are not released into the environment. Extraction is therefore an important component of the overall system and ensures health protection, occupational safety, and environmental protection in electroplating.

[0005] Capturing hazardous substances and determining the required air volumes are important factors for complying with legally prescribed air quality limits. At the point where hazardous substances are to be captured and removed, the extraction air volume must meet a minimum air velocity. This minimum air velocity must be greater than the velocity of the rising hazardous substances. Furthermore, any crossflows 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 installed above the basin to directly capture the rising vapors and / or aerosols. This hood is either permanently installed or movable, allowing it to be positioned over the basin as needed.

[0007] With the edge extraction 1*, as shown in the example 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 (single-sided edge extraction) or both edges (double-sided edge extraction) of the basin 50* directly above the process liquid. Edge extraction is particularly effective for capturing aerosols and gases directly at the source before they escape into the ambient air. However, the suction effect decreases significantly with the distance between the extraction opening in the exhaust air unit and the hazardous material location. Therefore, a high exhaust air volume flow is required to compensate.

[0008] There are also so-called push-pull systems, which are a special type of edge extraction and are used in electroplating. These systems are designed to capture rising vapors more effectively than single- or double-sided edge extraction. On one side of the tank, fresh air is blown over the tank surface via a nozzle or air duct. This air is typically blown in at a relatively low velocity, creating an "air curtain" over the tank. On the opposite side of the tank, there is an extraction bar or extraction duct. The extraction should be adjusted to efficiently capture the entire air flow coming from the push side, as well as the transported vapors and aerosols. The push-pull system is attached to the edges of the electroplating or anodizing tank, with the air supply and extraction along the long sides.The system is mounted using sturdy, corrosion-resistant brackets or supports, which are attached either directly to the tank frame or via additional support structures. Push-pull systems carry the risk of airflow being reflected back during loading and unloading of workpieces from the electrolyte bath, preventing contaminants from being dispersed and captured. Likewise, the extraction flow rate must be very high to prevent the escape of harmful gases, which is why push-pull systems typically require a lot of energy.

[0009] Because the fumes in electroplating are often very aggressive, the materials used for the hood or edge extraction system must be corrosion-resistant. The extracted fumes and gases are removed through a network of ducts. High-performance fans ensure that the air is extracted continuously and with sufficient flow rate. These ducts lead to a central exhaust system, where the air is filtered and cleaned 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 is not functioning adequately, warning signals are issued or the system is automatically shut down to avoid dangerous situations.

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

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

[0013] These and other objects 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 a galvanizing process in a galvanizing 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 a galvanizing or anodizing tank. The air supply unit is designed to emit air supply jets parallel to the surface of a process liquid contained in the galvanizing or anodizing tank during intended use of the device, and the exhaust air unit is designed to extract the air supply jets enriched with vapors and / or aerosols. According to the invention, the air supply unit has a plurality of air supply openings for emitting the air supply jets and at least one pressure chamber fluidly connected to the plurality of air supply openings.The invention further provides that at least one of the supply air 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 flow direction which is at least 3 times the hydraulic diameter of a cross-sectional area, seen perpendicular to the flow direction, of the at least one supply air 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 a plating tank and during the anodic oxidation of aluminum components in an anodizing tank. Because the supply air flows through a duct with a length L that 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 liquid. These jets are, so to speak, "given" a direction that is significantly more pronounced than air jets that only have to pass through a shorter duct.The supply air jets are already so strongly directed as they exit the supply air openings that they are as close as possible to the process fluid, resulting in particularly efficient capture of rising vapors and / or aerosols. This also results in energy savings, as the exhaust air unit can be operated at a lower volume flow without compromising the safety of the extraction system.

[0016] In contrast to conventional push-pull systems, which only emit free jets roughly toward the exhaust air unit, the invention emits directed supply air jets from the supply air 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 a non-directional free jet is the airflow emitted into the room by a fan or blower. Non-directional free jets are ideal for applications where a wide distribution of a medium is desired, e.g., for general ventilation of a room or for cooling large areas. However, they are less suitable when precise control or concentration of the jet is required.A directed beam, on the other hand, is a beam that is specifically focused and directed in a specific direction by mechanical devices such as nozzles, pipes or channels.

[0017] The supply air 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 be able to compare different ducts with different cross-sectional shapes fluid dynamically, the so-called hydraulic diameter is used. The term "hydraulic diameter" is familiar to those skilled in the art and represents a calculated value that indicates the diameter of a flow duct with any cross-section that, at the same length and the same average 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 duct has a length L in the flow direction that is at least 3 to 11 times the hydraulic diameter of the cross-sectional area, perpendicular to the flow direction, of the at least one supply air opening. Such a duct imparts an even more pronounced directional 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 of the plurality of air inlets are each fluidly connected to the at least one pressure chamber via an elongated channel, and if each channel has a length L in the flow direction that is at least three times the hydraulic diameter of a cross-sectional area, perpendicular to the flow direction, of the associated air inlet. This achieves very efficient extraction across 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 flow direction that is at least 4 times to 11 times the hydraulic diameter of the cross-sectional area, seen perpendicular to the flow direction, of the corresponding supply air opening.

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

[0022] According to a further preferred embodiment, a cross-sectional area of ​​the at least one supply air opening, seen perpendicular to the flow direction, preferably of all supply air openings, is in a range of 1 mm 2 up to 5 mm 2 . A jet outlet opening with such a small cross-section achieves a high jet exit speed despite a low jet volume flow, which results in a greater range of the jet (up to the opposite suction opening).

[0023] Preferably, an outlet end of the at least one channel, preferably all channels, facing the electroplating or anodizing tank is tapered. By tapering the outlet end, the air in the channel is accelerated evenly, which leads to reduced flow resistance and further increases the effect of directed movement of the supply air.

[0024] It is advantageous if the plurality of supply air openings are arranged along the longitudinal axis in the supply air unit such that, when the device is used as intended, all of the plurality of supply air openings are at the same distance from the process liquid surface. As a result, the supply air jets create a directed and focused air curtain above the process liquid, consisting of a plurality of individual jets that have merged into a single jet. This air curtain maintains a constant distance from the process liquid along the longitudinal side of the tank and has a strongly directed movement component toward the exhaust air unit.

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

[0026] If the plurality of supply air openings are preferably fluidly connected to only one pressure chamber, the manufacturing costs of the supply air unit are reduced. Furthermore, a pressure source that generates the supply air jets only needs to be fluidly connected to one pressure chamber of the supply air 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 that can be generated by an electric fan is sufficient. A supply air volume flow generated by an electric fan is significantly more energy-efficient than a volume flow typically generated by a compressed air system permanently installed in a building, leading to further energy savings.

[0028] Preferably, the supply air openings of the plurality of supply air openings are evenly spaced from one another along the longitudinal axis of the supply air unit. This allows for a more homogeneous extraction of the vapors and / or aerosols along the longitudinal side of the basin.

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

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

[0031] In the drawings, identical reference numerals or reference numerals belonging to a series indicate identical or functionally corresponding structural components of the device according to the invention.

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

[0033] The shape of the electroplating or anodizing tank plays a rather minor 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 a plating or anodizing tank 50 with an attached supply air unit 10 and exhaust air 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 an interior space 52 that is open on one side.

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

[0036] The supply air unit 10 and / or the exhaust air unit 20 are preferably cuboid-shaped. The cuboid-shaped 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 wall 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 fluidly connected to a duct 14 arranged inside the cuboid-shaped housing of the supply air unit 10, while the exhaust air openings 22 are preferably fluidly connected to a duct arranged inside the cuboid-shaped housing of the exhaust air unit 20.

[0037] In Fig.2, only the plurality of exhaust air openings 22 of the exhaust air unit 20 can be seen, which are preferably slit-shaped. The shape of the exhaust air openings 22 can, however, also be circular, round, oval or another shape. The exhaust air unit 20, preferably the duct arranged inside the cuboid-shaped housing of the exhaust air unit 20, is fluidly connected to a vacuum source, such as a pump, in order to generate a vacuum inside or in the region of the exhaust air openings 22 of the exhaust air unit 20, which causes any vapors and / or aerosols that arise during the galvanization process to be extracted through the exhaust air unit 20. The supply air unit 10, preferably the duct 14 arranged inside the cuboid-shaped 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), even more preferably a radial compressor.

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

[0039] Each air supply opening 12 has an inlet end 12a and an outlet end 12b. The inlet end 12a and the outlet end 12b are fluidly connected via an elongated channel 12c. The channel 12c has a length L. Fig. The side wall 11 of the supply air unit 10 shown in Figure 3 represents the inside and Fig. 2 not visible, facing the inside of the basin 52 inner wall of the Fig. 2 shows the supply air unit 10.

[0040] As in Fig. 3 is indicated by dashed lines, the longitudinal axis of the channel 12c does not have to run perpendicular to those end faces of the wall 11 on which 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 duct length L is at least 3 times, preferably at least 4 times to 11 times, the hydraulic diameter of a cross-sectional area, viewed perpendicular to the flow direction, of the corresponding supply air opening 12, preferably the cross-sectional area of ​​the outlet end 12b of the supply air opening 12. This has the effect of "giving" the supply air jets a direction that is significantly more pronounced than with air jets that only have to pass through a shorter duct. This reduces the opening angle of the supply air jets spreading over the process liquid. In other words, the supply air jets are already so strongly directed at the time they leave the supply air openings 12 that they are as close as possible to the process liquid, which leads to 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 supply air 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 familiar to those skilled in the art and represents a calculated value that indicates the diameter of a flow duct with any cross-section that, at the same length and the same average flow velocity, exhibits the same pressure loss as a flow pipe with a circular cross-section and the same diameter.

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

[0044] The inlet end 12a of the supply air opening 12 is provided with a pressure chamber 14 ( Fig. 5) are 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 line (not shown). In this case, the hose line 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 bevel 13, which preferably has an angle of 45° to the longitudinal axis of the duct 12c. This angle can also be smaller or larger than 45°. Preferably, the outlet end 12b of at least one supply air opening 12, preferably all supply air openings 12, is tapered, whereby the supply air flowing through the duct 12c to the outlet end 12b is further accelerated at the outlet end 12b.

[0046] The Fig. 4 and the Fig. 5 show an exemplary experimental comparison of the conventional double-sided edge suction ( Fig. 4) and the active flow guidance with directed discharge of the supply air jets from the supply air unit 10 in the direction of the exhaust air unit 20 according to the invention ( Fig. 5).

[0047] If, for a given size of the electroplating or anodizing tank 50*, 50 and for a given electroplating process, an exhaust air volume flow of 1250 m 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, the total exhaust air volume flow for the double-sided edge extraction 20a*, 20b* is 2500 m 3 / h ( Fig. 4), while the exhaust air volume flow in the exhaust air unit 20 according to the invention continues to be 1250 m 3 / h is ( Fig. 5). The supply air jets in Fig. 5 are generated by means of an electric fan or radial compressor 40.

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

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

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

[0051] Blow-out - Centrifugal compressor: 0.01 kWh / m 3 - Electric fan (small): 0.0012 kWh / m 3 Conventional pelvic suction Pool suction with active flow control Ventilator alt: 0,00125 kWh / m 3 × 2.500 m 3 / h = 3.125 W ⇨ Old fan: 0.00125 kWh / m 3 × 1,250 m 3 / h = 1,560 W + centrifugal compressor: 0.01 Wh / m 3 × 15 m 3 / h = 150 W Σ = 1,710 W -> 45% savings potential Ventilator modern: 0,0005 kWh / m 3 x 2.500 m 3 / h = 1.250 W ⇨ Modern fan: 0.0005 kWh / m 3 x 1,250 m 3 / h = 625 W + small electric fan: 0.0012 Wh / m 3 x 15 m 3 / h = 18 W Σ = 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 directed airflow 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 pollution in the work environment and improves employee safety.

[0053] Compared to traditional edge extraction systems, which require large volumes of air to capture vapors and / or aerosols, the invention enables more precise and targeted extraction. This requires less exhaust air flow, thus reducing energy consumption.

[0054] Because the invention directs the airflow over the tank surface, the risk of the process fluid being disturbed by strong air movements is minimized. This ensures 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 tank. It can be easily integrated into existing systems and adapted to different tank sizes and processes.

Claims

[1] Device (1) for extracting vapors and / or aerosols rising during a galvanizing process in a galvanizing or anodizing tank (50), comprising a supply air unit (10) having a longitudinal axis and an exhaust air unit (20) which can be attached to opposite sides of a galvanizing or anodizing tank (50), wherein the supply air unit (10) is designed to emit supply air jets parallel to the surface of a process liquid (30) contained in the galvanizing or anodizing tank (50) during the intended use of the device (1), and the exhaust air unit (20) is designed to extract the supply air jets enriched with vapors and / or aerosols, and wherein the supply air unit (10) has a plurality of supply air openings (12) for emitting the supply air jets and at least one pressure chamber (14) which is fluidly connected to the plurality of supply air openings (12). characterized bythat at least one of the supply air 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 flow direction which is at least 3 times the hydraulic diameter of a cross-sectional area, seen perpendicular to the flow direction, of the at least one supply air opening (12), whereby the supply air jet enriched with vapors and / or aerosols can be captured by the exhaust air unit (20). [2] Device (1) according to claim 1, wherein the channel (12c) has a length L in the flow direction which is at least 3 times to 11 times the hydraulic diameter of the cross-sectional area, seen perpendicular to the flow direction, of the at least one air inlet opening (12). [3] Device (1) according to claim 1 or 2, wherein all supply air openings (12) of the plurality of supply air openings (12) are each fluidically 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 flow direction which is at least 3 times the hydraulic diameter of a cross-sectional area, seen perpendicular to the flow direction, of the associated supply air opening (12). [4] Device (1) according to claim 3, wherein each channel (12c) has a length L in the flow direction which is at least 4 times to 11 times the hydraulic diameter of the cross-sectional area, seen perpendicular to the flow direction, of the associated supply air opening (12). [5] Device (1) according to claim 3 or 4, wherein each channel (12c) has the same length L. [6] Device (1) according to one of the preceding claims, wherein a cross-sectional area of ​​the at least one supply air opening (12), seen perpendicular to the flow direction, preferably of all supply air openings (12), is in a range of 1 mm 2 up to 5 mm 2 lies. [7] Device (1) according to one of the preceding claims, wherein an outlet end (12b) of the at least one channel (12c), preferably all of the channels (12c), facing the electroplating or anodizing tank (50) is tapered. [8] Device (1) according to one of the preceding claims, wherein the plurality of supply air openings (12) are arranged along the longitudinal axis in the supply air unit (10) such that, during the intended use of the device (1), all supply air openings (12) of the plurality of supply air openings (12) have the same distance from the process liquid surface (30). [9] Device (1) according to one of the preceding claims, wherein the plurality of supply air openings (12) have a circular, round, oval, rectangular or polygonal shape. [10] Device (1) according to one of the preceding claims, wherein the plurality of supply air openings (12) are fluidly connected to only one pressure chamber (14). [11] Device (1) according to one of the preceding claims, wherein the pressure chamber (14) is fluidly connected to an electric fan (40). [12] Device (1) according to one of the preceding claims, wherein the supply air openings (12) of the plurality of supply air openings (12) are evenly spaced from one another along the longitudinal axis of the supply air unit (10). [13] Device (1) according to claim 12, wherein the distance between two supply air openings (12) adjacent along the longitudinal axis of the supply air unit (10) is such that the supply air jets emerging from the plurality of supply air openings (12) combine to form a single flat jet which covers the entire surface of the process liquid (30) contained in the electroplating or anodizing tank.

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