DEVICE FOR DRY ICE TREATMENT OF SURFACES AND METHOD FOR TREATING SURFACES

Description

[0001] The invention relates to a device for dry ice treatment and, in particular, dry ice cleaning of surfaces, as well as a corresponding method. Devices for dry ice cleaning of surfaces are generally known. In such devices, which are occasionally also referred to as dry ice blasting systems, a dry ice jet is generated in which dry ice particles, such as dry ice pellets, are accelerated by compressed air to a speed of approximately 300 meters per second and shot onto the surface to be cleaned, where they create a localized thermal shock. The coating to be removed, such as, in particular, contaminants, on the surface to be cleaned contracts in the process, and the following dry ice particles, in conjunction with the kinetic energy they contain, cause the contaminants to flake off. The dry ice particles sublimate immediately upon impact, leaving a dry surface.

[0002] Dry ice is made from liquid CO2. In a pelletizer, liquid CO2 is expanded under controlled conditions. This physical process creates dry ice snow. This snow is pressed through an extruder plate into round, hard pellets with elongated grains ranging in diameter from 1.7 mm to 3.0 mm. Dry ice has a temperature of approximately -79°C. Carbon dioxide (CO2) is an odorless, non-flammable gas that is 1.5 times heavier than air. The Earth's atmosphere normally contains approximately 0.03% CO2. Today, CO2 is mainly produced as a byproduct of various chemical processes and is stored in tanks after extraction.

[0003] Dry ice blasting systems represent a modern alternative to conventional industrial cleaning methods. A unique feature of using dry ice as a blasting agent is that the dry ice particles transform into a gas, or sublimate, the moment they hit the surface to be cleaned. This means that the surface is left dry and clean after treatment, with no cleaning or blasting agent residue. Because it is a completely dry and powerless process, dry ice blasting can be used in areas where other methods are unsuitable. For example, electric motors and technical systems with electrical, pneumatic, and hydraulic components can be cleaned without the need for shutdown or disassembly.In addition, dry ice blasting is suitable for a variety of other applications, such as cleaning machines, electrical installations, any surfaces and shapes.

[0004] During cleaning, dry ice particles are accelerated to the speed of sound using compressed air before hitting the surface to be treated. The cleaning effect is achieved through three different factors mentioned above: first, the coating is dislodged and bursts apart when the dry ice particles hit the surface at the speed of sound – a kinetic effect.

[0005] Secondly, the low temperature of the dry ice particles makes the coating brittle, leading to cracking and contributing to its detachment, as the bond between the coating and the underlying surface is weakened. This allows dry ice to penetrate beneath the coating—a thermal effect.

[0006] Third, the dry ice penetrates the coating and instantly evaporates, causing it to expand approximately 700 to 1,000 times in volume. This explosive reaction lifts the coating from the surface—a sublimation effect / explosion effect. A moist layer, such as oil or grease, is carried away by the air stream—similar to high-pressure cleaning. However, unlike high-pressure cleaning, the cleaned surface is left dry and clean.

[0007] Because dry ice evaporates immediately upon impact with the surface being treated, leaving no residue, only the removed layer needs to be disposed of after dry ice blasting. This can usually be swept up from the floor beneath the treated object or removed with a vacuum cleaner.

[0008] Dry ice blasting can be considered an alternative to high-pressure cleaning and other conventional blasting methods that use various blasting media, such as sand, water, glass, or plastic granules. It is ideal for removing glue, paint, oil, grease, coal dust, soot, lubricants, and bitumen.

[0009] Dry ice blasting does not use any hazardous chemicals or solvents. Therefore, operators are not exposed to fumes or similar substances during the cleaning process. There are also no disposal costs for such chemicals.

[0010] Even though dry ice blasting is gentler on materials and surfaces than high-pressure cleaning and other conventional blasting methods that use various blasting media, the areas of application and use of dry ice blasting technology are significantly limited when compared to high-pressure cleaning and other conventional blasting methods that use various blasting media. Currently available dry ice blasting systems are particularly unsuitable for cleaning or treating surfaces in sensitive areas. Sensitive areas in this context include, in particular, areas located in clean rooms or areas of gas turbines, for example. A gas turbine comprises one or more compressor stages that compress the ambient air, a combustion chamber that burns fuel together with the compressed air, and one or more turbine stages to supply the compressors. The expanding combustion gases drive the turbine, resulting in thrust for propulsion.

[0011] Jet engines typically have a turbofan located upstream of the compressor stages and significantly larger in diameter than the compressor stages. The turbofan is also driven by the turbine stages and allows a significant portion of the total airflow through the engine to bypass the compressor stages, combustion chamber, and turbine stages as a so-called bypass airflow. This bypass airflow can significantly increase the efficiency of an engine and reduce noise levels.

[0012] In addition, conventional dry ice blasting systems show limitations when it comes to treating textiles or other open-pored objects, Plexiglas, highly polished aluminum and especially ceramics, ceramic honeycombs from 3D production, circuit boards and printed circuit boards.

[0013] The document DE 10 2010 064 406 A1 relates to a device and a method for pressure blasting by means of a mixture jet of frozen particles and a carrier gas.

[0014] The document DE 20 2005 018 952 U1 relates to a dry ice blasting system. DE 20 2005 018 952 U1 discloses a dry ice blasting device having the features of the preamble of claim 1 and a method for treating surfaces with such a device.

[0015] The publication WO 2015 / 079409 A1 relates to a filter unit for filtering compressed air mixed with oil.

[0016] The document US 9,446,500 B2 concerns an abrasive water jet technology.

[0017] The invention is based on the problem that when cleaning such jet engines or corresponding gas turbine engines, care must be taken to ensure that no residues are deposited in the turbine being cleaned during the cleaning process. The same applies, figuratively speaking, when using a cleaning process in a cleanroom, for surfaces used in food technology or in the pharmaceutical industry. A similar problem of achieving the most complete, residue-free cleaning possible exists in the pharmaceutical sector. The same also applies, for example, to systems used to manufacture semiconductors or other electronic components.

[0018] Accordingly, the object of the present invention is to provide a device for dry ice treatment and in particular dry ice cleaning of surfaces, whereby a wider application is possible while avoiding the aforementioned disadvantages of conventional dry ice blasting systems.

[0019] In particular, the invention is therefore based on the object of specifying a device and a method for dry ice treatment and in particular dry ice cleaning of surfaces, wherein no residues remain after cleaning or treatment of the corresponding surface, so that the cleaning or treatment therapy can also be used for sensitive components, in particular for components in clean room environments.

[0020] With regard to the device, the object underlying the invention is achieved by the subject matter of independent patent claim 1, with advantageous developments of the device according to the invention being specified in the corresponding dependent claims. With regard to the method, the object underlying the invention is achieved by the subject matter of the independent patent claim 12.

[0021] The invention is based on the discovery that the ambient air used to provide the compressed air required for the cleaning process contains foreign particles in the form of, for example, aerosols, pollen, insects, hydrocarbons from combustion-powered vehicles and industrial sources, as well as salts from marine sources. In conventional dry ice blasting systems, the ambient air containing these particles is compressed as compressed air and used in the subsequent dry ice treatment process.

[0022] The contaminants contained in the ambient air (e.g., aerosols, pollen, insects, hydrocarbons, salts, etc.) are concentrated in the compressed air and applied to the surface to be treated / cleaned along with the dry ice particles. The contaminant particles follow the path of the compressed air (compressed air) or the dry ice particle-compressed air mixture and settle on the various surfaces / components in the area to be treated / cleaned. This contamination leads, for example, to a change in the properties of the boundary layer airflow, for example, in the compressor components of engines. Furthermore, the contamination of a jet engine leads to a reduction in efficiency and thus to increased fuel consumption and increased environmental pollution.

[0023] The use of dry ice blasting technology in clean rooms or in rooms used for food processing or for the production / processing of pharmaceuticals is therefore currently excluded.

[0024] Accordingly, the invention relates to a device for dry ice treatment and in particular for dry ice cleaning of surfaces, wherein the device comprises a dry ice source for providing dry ice, in particular in the form of dry ice particles (granules or pellets), a mixing unit fluidly connected or connectable to the dry ice source, and a compressed air source fluidly connected or connectable to the mixing unit for providing compressed air for the mixing unit. In the mixing unit, a dry ice particle-compressed air mixture is generated using the compressed air provided by the compressed air source and the dry ice provided by the dry ice source, which mixture can be applied to the surface to be treated for dry ice treatment and in particular for dry ice cleaning.

[0025] In order to ensure that dry ice technology can also be used in sensitive areas, in particular clean rooms or in food or pharmaceutical areas, a conditioning unit is assigned to the compressed air source according to the invention in order to condition the compressed air provided to the mixing unit as required or according to application, specifically with regard to the size and concentration of solid particles still contained in the compressed air provided, with regard to the pressure dew point and the moisture content of the compressed air provided and with regard to a residual amount of oil aerosols and hydrocarbons that may still be contained in the compressed air provided.

[0026] In order to adjust the degree of treatment of the compressed air to be provided by the compressed air source, the conditioning unit has a variety of different operating states, which can be selected, in particular, via a manual input device. According to the invention, the conditioning unit can be selectively operated in at least one of the following operating states: in a first operating state in which the compressed air provided by the compressed air source may still contain solid particles with a size greater than 5 µm, or in a second operating state in which the compressed air provided by the compressed air source may still contain solid particles with a size of up to a maximum of 5 µm according to ISO 8573-1:2010.

[0027] The second operating state of the conditioning device is selected in particular when the degree of purity of the compressed air to be provided by the compressed air source must be particularly high in order to effectively prevent foreign substances from entering the area in which the dry ice technology is used during the dry ice treatment.

[0028] According to the invention, it is provided in this context that the conditioning device has a filter device, wherein the filter device has at least one pre-filter and at least one post-filter, wherein - depending on the selected operating state of the conditioning device - at least the at least one post-filter for compressed air treatment can be switched on or off optionally or as required.

[0029] This is a particularly easy-to-implement solution that allows the device to be switched and operated for different applications. Of course, other solutions are also possible. According to embodiments of the device according to the invention, the conditioning unit can be operated selectively in at least one of the following purity classes: in purity class 01 according to ISO 8573-1:2010, in which the compressed air provided by the compressed air source has a maximum of 20,000 particles with a particle size greater than 0.1 µm and a maximum of 0.5 µm, a maximum of 400 particles with a particle size greater than 0.5 µm and a maximum of 1.0 µm and a maximum of 10 particles with a particle size greater than 1.0 µm and a maximum of 5.0 µm per m 3 of compressed air provided; in purity class 02 according to ISO 8573-1:2010, in which the compressed air supplied by the compressed air source has a maximum of 400,000 particles with a particle size greater than 0.1 µm and a maximum of 0.5 µm, a maximum of 6,000 particles with a particle size greater than 0.5 µm and a maximum of 1.0 µm, and a maximum of 100 particles with a particle size greater than 1.0 µm and a maximum of 5.0 µm per m3 of compressed air supplied; and / or in purity class 03 according to ISO 8573-1:2010, in which the compressed air supplied by the compressed air source has a maximum of 90.000 particles with a particle size greater than 0.5 µm and a maximum of 1.0 µm and a maximum of 1,000 particles with a particle size greater than 1.0 µm and a maximum of 5.0 µm.

[0030] Because the conditioning unit can be operated selectively in the aforementioned cleanliness classes 01 to 03, it is possible to select dry ice treatment for surfaces in areas where the corresponding cleanliness classes must be maintained. This requires no complex retrofitting or conversion of the device. Accordingly, the field of application of dry ice technology is further expanded with this advanced development.

[0031] Alternatively or additionally, the conditioning unit is designed, in particular, to selectively adjust the pressure dew point of the compressed air provided by the compressed air source in order to prevent or at least reduce the penetration of moisture into the area where the dry ice technology is applied.

[0032] To set a pressure dew point of the compressed air provided by the compressed air source, the conditioning unit has at least one water separator that can be selectively switched on or off for compressed air treatment, at least one heat-regenerating absorption dryer that can be selectively switched on or off for compressed air treatment, at least one refrigeration dryer that can be selectively switched on or off for compressed air treatment, and / or at least one membrane dryer that can be selectively switched on or off for compressed air treatment, in particular with an integrated nanofilter.

[0033] With this implementation, the conditioning unit can be operated in at least one of the following moisture purity classes: in a first humidity purity class in which the pressure dew point of the compressed air provided by the compressed air source is at least -70 °C; in a second humidity purity class in which the pressure dew point of the compressed air provided by the compressed air source is at least -40 °C; and / or in a third humidity purity class in which the pressure dew point of the compressed air provided by the compressed air source is at least -20 °C.

[0034] Alternatively or additionally, according to further developments of the device according to the invention, it is provided that the conditioning unit and / or compressed air source are / is designed, in particular, to selectively adjust a purity of the compressed air provided by the compressed air source with regard to a total concentration of oil aerosols and hydrocarbons.

[0035] In order to implement this in a particularly simple manner, according to further developments of the last-mentioned embodiment, it is provided that the compressed air source has an oil-lubricated, compressing compressor unit and an oil-free compressing compressor unit, wherein depending on a selected purity of the compressed air to be provided by the compressed air source for compressing intake air, either the oil-lubricated, compressing compressor unit or the oil-free compressing compressor unit is controlled.

[0036] Overall, it is advantageous in this context if, in order to adjust the total oil concentration purity of the compressed air provided by the compressed air source, the conditioning unit can be operated in at least one of the following total oil concentration purity classes: in a first total oil concentration purity class in which the compressed air provided by the compressed air source contains a maximum of 0.01 mg of oil per m3; in a second total oil concentration purity class in which the compressed air provided by the compressed air source contains a maximum of 0.1 mg of oil per m3; and / or in a third total oil concentration purity class in which the compressed air provided by the compressed air source contains a maximum of 1.0 mg of oil per m3.

[0037] Alternatively or additionally, it is conceivable that, in order to adjust the total oil concentration purity of the compressed air provided by the compressed air source, the conditioning unit has at least one coalescing filter that can be selectively switched on or off for compressed air treatment and / or at least one activated carbon filter that can be selectively switched on or off for compressed air treatment.

[0038] According to a further aspect of the present invention, it is provided that the device has a control and / or regulating device for controlling and / or regulating the compressed air source and / or the conditioning unit associated with the compressed air source such that, with regard to the degree of purity, the compressed air provided by the compressed air source corresponds to a predefined or definable degree of purity.

[0039] The invention further relates to a method for treating surfaces, in particular for cleaning and / or finishing surfaces, wherein the device according to the invention discussed above is used for this purpose, and wherein the method comprises the method step of providing dry ice, in particular in the form of dry ice particles, the method step of providing compressed air, the method step of producing a dry ice particle-compressed air mixture from the provided dry ice and the provided compressed air, and the method step of applying the dry ice particle-compressed air mixture to the surface to be treated.

[0040] In the method according to the invention, it is particularly provided that the compressed air provided for producing the dry ice particle-compressed air mixture is conditioned, in particular in a demand- or application-specific manner and in particular with regard to the size and concentration of solid particles still contained in the provided compressed air, with regard to the pressure dew point and / or the moisture content of the provided compressed air and / or with regard to a residual amount of oil aerosols and hydrocarbons that may still be contained in the provided compressed air.

[0041] An exemplary embodiment of the device according to the invention is described in more detail below with reference to the drawings.

[0042] They show: FIG. 1a-c schematically shows the method according to the invention for treating surfaces, in particular for cleaning and / or finishing surfaces; and FIG. 2 schematically shows an exemplary embodiment of the device according to the invention for treating surfaces, in particular for cleaning and / or finishing surfaces.

[0043] The FIG. 2 The schematically shown exemplary embodiment of the device 1 according to the invention has a dry ice source 2 for providing dry ice, in particular in the form of dry ice particles, a compressed air source 4 and a mixing unit 3, wherein the mixing unit 3 is fluidly connected to the dry ice source 2 on the one hand and the compressed air source 4 on the other hand and serves to generate a dry ice particle-compressed air mixture 14 from the dry ice provided by the dry ice source 2 and the compressed air provided by the compressed air source 4.

[0044] According to the invention, a conditioning unit 5 is also used, with which a dry ice particle-compressed air mixture 14 provided or to be provided by the mixing unit 3 can be adapted to application-specific conditions before the dry ice particle-compressed air mixture 14 is applied to the surface to be treated.

[0045] The FIG. 2 The schematically shown dry ice source 2 may comprise a device 1 for generating solid CO2 particles. This device 1 may comprise, for example, a snow chamber having an inlet for CO2 and a compressor for compressing CO2 snow located in the snow chamber. In this context, it is conceivable that the snow chamber is closed on one side by a matrix provided with openings.

[0046] Alternatively, it is also conceivable that the dry ice source 2 of the device 1 according to the invention has a storage container for storing dry ice particles the size of rice grains, so-called CO2 pellets.

[0047] CO2 pellets are produced by taking liquid carbon dioxide from an insulated tank, in which the carbon dioxide is stored at a pressure typically between 12 and 22 bar, and expanding it to atmospheric pressure via nozzles in a snow chamber. As the liquid carbon dioxide expands, a mixture of CO2 snow and cold CO2 gas is created. The gas phase is separated from the CO2 snow, and the CO2 snow is compressed using a compressor. A piston compressor, for example, is used for this purpose. The resulting dry ice block is then forced through a die to create solid CO2 strands, which are then cut into pellets approximately the size of a grain of rice using a suitable crushing tool.

[0048] The dry ice particles provided by the dry ice source 2, such as dry ice pellets, are metered into a compressed air stream provided by the compressed air source 4 in the mixing unit 3 and conveyed with this to a jet nozzle. In the device 1 according to the invention, the compressed air stream has a pressure between 0.1 bar and 24 bar, while the dry ice particles (CO2 pellets) are at atmospheric pressure. A pressure lock is preferably used to meter the dry ice particles into the compressed air stream, which is shown in the schematic drawing according to FIG. 2 is not shown.

[0049] When applying the dry ice particle-compressed air mixture 14 generated in the mixing unit 3 of the device 1 according to the invention to the surface 12 to be treated, the dry ice particles in the dry ice particle-compressed air mixture 14 are accelerated by means of the compressed air provided by the compressed air source 4, and the dry ice particle compressed air stream is - as in FIG. 1a indicated - directed towards the surface 12 to be cleaned or treated.

[0050] According to the invention, in this context, it is provided that a conditioning unit 5 is assigned to the compressed air source 4 in order to condition the compressed air provided to the mixing unit 3, in particular as required or according to application, in particular with regard to the size and concentration of solid particles still contained in the compressed air provided, with regard to the pressure dew point and / or the moisture content of the compressed air provided and / or with regard to a residual amount of oil aerosols and hydrocarbons that may still be contained in the compressed air provided.

[0051] In order to adjust the degree of treatment of the compressed air to be provided by the compressed air source 4, the conditioning unit 5 has a plurality of different operating states which can be selected in particular via a manual input device.

[0052] In this context, the invention provides that the conditioning unit 5 can be operated selectively in one of the following operating states: in a first operating state in which the compressed air provided by the compressed air source 4 may still contain solid particles with a size greater than 5 µm; or in a second operating state in which the compressed air provided by the compressed air source 4 may still contain solid particles with a size of up to max. 5 µm according to ISO 8573-1:2010.

[0053] At the FIG. 2 In the embodiment of the device 1 according to the invention shown, the conditioning unit 5 has a filter device 7 with a pre-filter and a post-filter. Depending on a selected operating state of the conditioning unit 5, the at least one post-filter for compressed air treatment can be switched on or off.

[0054] The conditioning unit 5 of the device 1 according to the invention is further designed, in particular, to selectively adjust the pressure dew point of the compressed air provided by the compressed air source 4.

[0055] For this purpose, the FIG. 2 In the schematically illustrated embodiment of the device 1 according to the invention, the conditioning unit 5 comprises at least one refrigeration dryer that can be selectively switched on or off for compressed air treatment. Instead of such a refrigeration dryer, it is also conceivable to use a water separator, an absorption dryer, and / or a membrane dryer.

[0056] In order to be able to adjust the purity of the compressed air provided by the compressed air source 4 with regard to a total concentration of oil aerosols and hydrocarbons, the filter device 7 already mentioned is designed accordingly.

[0057] Alternatively or additionally, it is also conceivable that the compressed air source 4 has an oil-lubricated, compressing compressor unit and an oil-free compressing compressor unit, wherein, depending on a selected purity of the compressed air to be provided by the compressed air source 4, either the oil-lubricated, compressing compressor unit or the oil-free compressing compressor unit is controlled for compressing intake air.

[0058] In FIG. 2 It is further indicated that the device 1 according to the invention has a control and / or regulating device 16 for controlling and / or regulating the compressed air source 4 and / or the conditioning unit 5 assigned to the compressed air source 4 in such a way that, with regard to the degree of purity, the compressed air provided by the compressed air source 4 corresponds to a predefined or definable degree of purity.

[0059] The compressed air source 4 of the device 1 according to the invention serves not only to supply a predetermined or definable amount of compressed air to the mixing unit 3 per unit of time, wherein the amount of compressed air supplied to the mixing unit 3 per unit of time depends in particular on the amount of dry ice particles supplied to the mixing unit 3 per unit of time, but also to meter a predetermined or definable amount of compressed air as additional compressed air 8 to the dry ice particle-compressed air mixture 14 generated by the mixing unit 3 per unit of time. This additional compressed air 8 serves in particular to vary the jet pressure and / or to adjust a speed of the dry ice particle-compressed air mixture 14.

[0060] According to further developments of the device 1 according to the invention, the compressed air source 4 is further designed to supply shaping air 9 to a manual or automatic spray gun 6, which serves to apply the conditioned dry ice particle-compressed air mixture 14 to the surface 12 to be treated, in order, for example, to form an enveloping flow which envelops the dry ice particle-compressed air mixture 14 and has a parallelizing or focusing effect.

[0061] As in FIG. 1b and FIG. 1cAs shown, the method according to the invention provides optimal cleaning or treatment of the surface 12 without foreign matter being impinged on the surface 12 by the compressed air. The low temperature of the sublimated dry ice leads to the formation of cracks in the coating 13 on the surface 12 to be treated and thus to the detachment of the coating 13. In addition, a sublimation region 15 is preferably selected in the immediate vicinity of the surface 12 so that it is cleaned due to the sublimation effect or due to the explosive effect when the dry ice particles sublimate.

[0062] The invention is not limited to the embodiment shown in the drawings, but results from a combination of all features disclosed herein within the scope of the appended claims. List of reference symbols

[0063] 1Dry ice treatment device 2Dry ice source 3Mixing unit 4Compressed air source 5Conditioning unit 6Spray gun 7Filter device 8Additional compressed air 9Shaping air 11Dry ice particle-compressed air mixture 12Surface 13Deposition to be removed (contamination) 14Dry ice particle-compressed air mixture 15Sublimation area 16Control / regulating device

Claims

1. A device (1) for dry ice treatment and, in particular, for dry ice cleaning of surfaces, wherein the device (1) comprises: - a dry ice source (2) for supplying dry ice, in particular in the form of dry ice particles; - a mixing unit (3) fluidly connected or connectable to the dry ice source (2); and - a compressed air source (4) fluidly connected or connectable to the mixing unit (3) for supplying compressed air to the mixing unit (3), in which a dry ice particle-compressed air mixture (14) is generated with the supplied compressed air and the supplied dry ice, which can be applied to the surface (12) to be treated for dry ice treatment and, in particular, for dry ice cleaning, wherein the compressed air source (4) is assigned a conditioning unit (5) for conditioning the compressed air supplied to the mixing unit (3) as required or depending on the application, namely with regard to the size and concentration of solid particles still comprised in the supplied compressed air, with regard to the pressure dew point and the moisture content of the supplied compressed air, and with regard to a residual amount of oil aerosols and hydrocarbons that may still be comprised in the supplied compressed air, characterised in that the conditioning unit (5) can be operated alternatively in one of the following operating states: - in a first operating state in which the compressed air supplied by the compressed air source (4) may still comprise solid particles having a size greater than 5 µm; or - in a second operating state, in which the compressed air supplied by the compressed air source (4) may still comprise solid particles having a size of up to a maximum of 5 µm according to ISO 8573-1:2010, and that the conditioning unit (5) comprises a filter device (7), wherein the filter device (7) comprises at least one pre-filter and at least one post-filter, wherein depending on the selected operating state of the conditioning unit (5), selectively or as required, at least the at least one post-filter can be switched on or off for compressed air conditioning.

2. The device (1) according to claim 1, wherein, for setting the degree of treatment of the compressed air to be supplied by the compressed air source (4), the conditioning unit (5) has a plurality of different operating states which can be selected in particular via a manual input device.

3. The device (1) according to claim 1 or 2, wherein the conditioning unit (5) can be operated selectively in at least one of the following purity classes: - in purity class 01 according to ISO 8573-1:2010, in which the compressed air supplied by the compressed air source (4) comprises per m3 of compressed air supplied a maximum of 20,000 particles having a particle size greater than 0.1 µm and a maximum of 0.5 µm, a maximum of 400 particles having a particle size greater than 0.5 µm and a maximum of 1.0 µm, and a maximum of 10 particles having a particle size greater than 10 µm and a maximum of 5.0 µm; - in purity class 02 according to ISO 8573-1:2010, in which the compressed air supplied by the compressed air source (4) comprises per m3 of compressed air supplied a maximum of 400,000 particles having a particle size greater than 0.1 µm and a maximum of 0.5 µm, a maximum of 6,000 particles having a particle size greater than 0.5 µm and a maximum of 1.0 µm, and a maximum of 100 particles having a particle size greater than 1.0 µm and a maximum of 5.0 µm; and / or - in purity class 03 according to ISO 8573-1:2010, in which the compressed air supplied by the compressed air source (4) comprises per m3 of compressed air supplied a maximum of 90,000 particles having a particle size greater than 0.5 µm and a maximum of 1.0 µm, and a maximum of 1,000 particles having a particle size greater than 1.0 µm and a maximum of 5.0 µm.

4. The device (1) according to anyone of claims 1 to 3, wherein the conditioning unit (5) is designed to, in particular selectively, adjust the pressure dew point of the compressed air supplied by the compressed air source (4).

5. The device (1) according to claim 4, wherein, for adjusting a pressure dew point of the compressed air supplied by the compressed air source (4), the conditioning unit (5) comprises at least one water separator which can be selectively switched on or off for compressed air treatment, at least one heat-regenerating adsorption dryer which can be selectively switched on or off for compressed air treatment, at least one refrigeration dryer that can be selectively switched on or off for compressed air treatment, and / or at least one membrane dryer, in particular with an integrated nanofilter, that can be selectively switched on or off for compressed air treatment.

6. The device (1) according to claim 4 or 5, wherein the conditioning unit (5) can be operated, in particular optionally, in at least one of the following humidity purity classes: - in a first humidity purity class, in which the pressure dew point of the compressed air supplied by the compressed air source (4) is at least -70 degrees Celsius; - in a second humidity purity class, in which the pressure dew point of the compressed air supplied by the compressed air source (4) is at least -40 degrees Celsius; and / or - in a third humidity purity class, in which the pressure dew point of the compressed air supplied by the compressed air source (4) is at least -20 degrees Celsius.

7. The device (1) according to anyone of claims 1 to 6, wherein the conditioning unit (5) and / or compressed air source (4) are / is designed, in particular optionally with regard to a total concentration of oil aerosols and hydrocarbons, to adjust a purity of the compressed air supplied by the compressed air source (4).

8. The device (1) according to claim 7, wherein the compressed air source (4) comprises an oil-lubricated, compressing compressor unit and an oil-free compressing compressor unit, wherein, depending on a selected purity of the compressed air to be supplied by the compressed air source (4) for compressing intake air, either the oil-lubricated, compressing compressor unit or the oil-free compressor unit is selectively actuated.

9. The device (1) according to claim 7 or 8, wherein, for setting a total oil concentration purity of the compressed air supplied by the compressed air source (4), the conditioning unit (5) can be operated, in particular selectively, in at least one of the following total oil concentration purity classes: - in a first total oil concentration purity class, in which the compressed air supplied by the compressed air source (4) comprises a maximum of 0.01 mg of oil per m3; - in a second total oil concentration purity class, in which the compressed air supplied by the compressed air source (4) comprises a maximum of 0.1 mg of oil per m3; and / or - in a third total oil concentration purity class, in which the compressed air supplied by the compressed air source (4) comprises a maximum of 1 mg of oil per m3.

10. The device (1) according to anyone of claims 7 to 9, wherein, for adjusting a total oil concentration purity of the compressed air supplied by the compressed air source (4), the conditioning unit (5) comprises at least one coalescing filter which can be selectively switched on or off for compressed air treatment and / or at least one activated carbon filter which can be selectively switched on or off for compressed air treatment.

11. The device (1) according to anyone of claims 1 to 10, wherein a control and / or regulating device (16) is provided for controlling and / or regulating the compressed air source (4) and / or the conditioning unit (5) assigned to the compressed air source (4) in such a way that, with regard to the degree of purity, the compressed air supplied by the compressed air source (4) corresponds to a predetermined or determinable degree of purity.

12. A method for treating surfaces (12), in particular for cleaning and / or finishing surfaces (12), wherein a device (1) according to anyone of claims 1 to 11 is used for this purpose, and wherein the method comprises the following method steps: - providing dry ice, in particular in the form of dry ice particles; - providing compressed air; - producing a dry ice particle-compressed air mixture (14) from the dry ice provided and the compressed air provided; and - applying the dry ice particle-compressed air mixture (14) to the surface (12) to be treated, wherein the compressed air provided for producing the dry ice particle-compressed air mixture (14) is conditioned as required or specific to the application and with regard to the size and concentration of solid particles still comprised in the supplied compressed air, with regard to the pressure dew point and moisture content of the supplied compressed air, and with regard to a residual amount of oil aerosols and hydrocarbons that may still be comprised in the supplied compressed air.