Method and apparatus for treating process air

Abstract

A method for treating process air from an industrial process having a mainstream, at least a portion of the process air being treated by the following method steps: a first condensation step, in which a first condensate is separated from the process air and fed to a first recovery process; and a second condensation step, performed after the first condensation step, in which a second condensate is separated from the process air and fed to a second recovery process, wherein a minimum temperature of the process air reached during the second condensation step is lower than a minimum temperature of the process air reached during the first condensation step.

Description

[Technical field]

[0001] The present invention relates to a method for treating process air from an industrial process. [Background technology]

[0002] Process air can be used as a medium during certain process steps for the production of products in order to bring about certain technical effects, such as drying in the process steps. During industrial processes, the process air can receive production materials, which are then released into the environment after leaving the industrial process. However, such production materials may contain pollutants that have a negative impact on the environment. In order to reduce the negative impact on the environment and also to comply with certain legal limits for pollutants in the exhaust air released into the environment, this exhaust air must be properly treated.

[0003] Treatment of process air from industrial processes includes air purification of solvents used in the industrial process. As mentioned above, such treatment may be required for regulatory reasons for discharging the air to the environment and / or for economic reasons for general reuse in other industrial processes, the latter being especially true when using particularly valuable solvents.

[0004] In the prior art, methods are known in particular which have a condensation step, in which the condensate is separated from the process air, so that the solvent can be recovered.

[0005] Canadian Patent Application Publication No. 2214542A1 shows how solvent can be recovered during the manufacture of lithium ion batteries by condensing it from solvent-laden process air. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Canadian Patent Application Publication No. 2214542A1 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention relates to a method for treating process air, in particular for recovering solvents used in industrial processes such as the manufacture of lithium-ion batteries, which method comprises a condensation step operating at different temperature levels, in which a condensate containing the solvent is separated from the process air and then fed to a recovery process. The present invention also relates to an apparatus for treating process air from an industrial process, in particular for carrying out the method according to the invention.

[0008] The invention is based on the object of providing an improved method for recovering condensate from process air. [Means for solving the problem]

[0009] This problem is solved according to the invention by a method for treating process air from an industrial process having a mainstream, in which at least a part of the process air is treated by the following method steps: a first condensation step, in which a first condensate is separated from the process air and fed to a first recovery process, and a second condensation step, which follows the first condensation step, in which a second condensate is separated from the process air and fed to a second recovery process, in which the minimum temperature of the process air reached during the second condensation step is lower than the minimum temperature of the process air reached during the first condensation step.

[0010] The inventors have found that, in particular for the recovery of the solvent-containing condensate, it is advantageous to treat the process air by two condensation steps, the process air being cooled in the second condensation step to a lower temperature than in the first condensation step. A two-stage treatment allows the process air to be treated more thoroughly, so that a higher proportion of the solvent can be separated from the process air than would be possible with a one-stage condensation process. The method according to the invention has proven to be particularly advantageous over alternative methods with a concentrator downstream of the first condensation step, in which the solvent is adsorbed by the concentrator, in particular when the adsorbed solvent has a relatively low vapor pressure.

[0011] This problem is solved according to the invention in an independent alternative with a method for treating process air from an industrial process having a mainstream and a side stream, whereby at least a part of the process air is treated by the following method steps: a first condensation step, whereby a first condensate is separated from the process air and fed to a first recovery process; a part of the process air is branched off into a side stream in a first branch after the first condensation step; furthermore, a part of the process air is further treated in a first further treatment step after the first condensation step, whereby the first further treatment step comprises a heat supply and / or a reduction in pressure and / or a second supply of air outside the mainstream; after the first further treatment step, a part of the process air is branched off into a side stream in a second branch, preferably by means of an auxiliary line, and fed to the process air in the side stream.

[0012] "Ein" and "eine" are to be read as indefinite articles within the scope of the present disclosure, unless expressly stated otherwise, and therefore can always also be read as "at least one". Thus, multiple first condensation steps can also be provided followed by multiple second condensation steps. The first or second condensation steps can also be understood in each case as a multi-stage first or multi-stage second condensation step. In particular, the first or second condensation step can comprise multiple condensation processes (see below). Directional indications such as "downstream" or "upstream" in the method generally refer to the direction of flow. For example, the expressions "after the first condensation step" or "before the second condensation step" should be understood as "downstream of the first condensation step" or "upstream of the second condensation step". The cooling circuit in particular comprises a heat source and a heat sink, whereby thermal energy can be transferred from the heat source to the heat sink. In particular, the heat sink can comprise the environment or a technical device, for example a heat exchanger or a heating device.

[0013] The method according to the invention is preferably suitable for treating process air involved in industrial processes, for example during drying of coatings for the manufacture of electrodes, separators and / or membranes for the manufacture of lithium-ion batteries, in particular for secondary batteries or fuel cells. During the method according to the invention, at least a part of the process air is fed into the main stream for the first condensation step. Preferably, the main stream represents a continuous flowing stream of the process air in the method. Preferably, the main stream comprises the stream led from the industrial process to the first condensation step, i.e. preferably the majority of the process air led to the first condensation step. In particular, the spatial extent of the main stream also comprises the flow space in which the first condensation step takes place. Preferably, the process air is completely treated during the process of the first condensation step.

[0014] In a further embodiment, the spatial extent of the main flow may also include a flow space in which a second condensation step takes place, in which case the main flow first passes through the first condensation step and then through the second condensation step.

[0015] However, it is particularly preferred that the second condensing step is located external to the main flow, so that the main flow only passes through the first condensing step and not the second condensing step.

[0016] The process air may be a gas mixture, in which at least one component is condensable. In particular, such components include a solvent. The solvent component may be, for example, N-methyl-2-pyrrolidone (NMP), triethyl phosphate (TEP), ethylene-acrylic acid copolymer (EAA), dimethylacetamide (DMAc), or water, acetone, or alcohol. During the first and second condensation steps, the process air is preferably passed through a heat exchanger, in which it is cooled, whereby heat can be released from the process air to the heat exchanger. During the cooling of the process air, aerosols are generated in the air, which then pass through an internal structure for the capture of droplets. Thereby, the solvent and / or water are condensed, captured, and then separated.

[0017] The first condensate separated from the process air is fed to the first recovery process after separation. The feeding to the first recovery process can also include some intermediate steps that serve the recovery. Such intermediate steps include capturing the condensate in the first condensation process or feeding it via a pipe to a container outside the device in which the condensation process is carried out. The first condensate can also be pumped directly to the recovery process. This can also include further intermediate steps such as cleaning, reactivation, purification or temperature regulation of the condensate. During feeding to the first recovery process, the condensate can be filtered to remove dirt and then chemically activated and brought to a predefined temperature. The first recovery process can preferably be started immediately after the separation and only includes discharging the condensate, for example into a recovery container, after which another subsequent process can take place. The first condensate is therefore not further purified during the first recovery process in this case, but is only removed from the process air after condensation.

[0018] The second condensate is preferably separated from the process air in a manner similar to the first condensate and fed to a second recovery process. The feeding of the second condensate to the second recovery process may preferably include several intermediate steps that aid in its recovery, similar to the first condensate.

[0019] The second recovery process, similar to the first recovery process, may also involve only the removal of the second condensate after separation, so that again it is not further purified.

[0020] The process air is at a lower temperature during the second condensation step than during the first condensation step. Thus, the temperature of the process air during the second condensation step can be lower on average than during the first condensation step. The process air has a minimum temperature of about 25° C., 20° C., 15° C. or less during the first condensation step. In contrast, during the second condensation step, the process air can reach a minimum temperature of −5° C. or less.

[0021] The condensation step may in particular comprise several cooling stages, i.e. several cooling elements or heat exchangers, for example connected in series, before the process air is heated again. In the case of multi-stage cooling of the process air in the condensation step, the lowest temperature reached should be considered as the lowest temperature over all cooling stages. Due to the different minimum temperatures reached during the first and second condensation steps, different solvent components of the process air, which have different dew points, can be separated separately in the first and second condensation steps, respectively. Preferably, the condensation steps are carried out in respective condensers, in particular all cooling stages of the condensation steps can be carried out in respective condensers. Preferably, the condensation step has at least two cooling stages, particularly preferably three cooling stages.

[0022] In a preferred embodiment, a coolant is used in a cooling stage for cooling the process air during the condensation step, whereby in the heat transfer in the cooling stage heat is removed from the process air and transferred to the coolant. The coolant can be a cooling fluid, in particular a cooling liquid, for example water. The coolant can be spatially separated from the process air, for example the coolant can circulate in a cooling circuit that is spatially separated from the process air. It is particularly preferred that the cooling stages in the condensation step have their own coolant, for example a first coolant in a first cooling stage and a second coolant in a second cooling stage. Optionally, the cooling stages can each have a separate cooling circuit. The heat removed from the process air during cooling can be added to the process air in a further treatment step. Heat transfer can thus be performed by the coolant between the condensation step and the further treatment step, so that thermal energy from the process air can be transferred from the condensation step to the further treatment step. The coolant, in particular the cooling liquid, can therefore ensure a high cooling capacity in the cooling stage. In particular, the cooling capacity in an air-water heat exchanger can be higher than in an air-air heat exchanger. Preferably, a coolant is already used in the first cooling stage to cool the process air, whereby the heat extracted from the process air in the first cooling stage is added to the process air in a further treatment step. The heat transfer can be realized simply by pumping the coolant. Optionally, the heat transfer can also be realized by a heat pump.

[0023] Alternatively or additionally, separation can also be considered in the sense of a condensation step, in which case, for example, before or during the condensation step, the pressure of the process air can be increased by a compression process using a compressor in order to also increase the partial pressure of the components. This allows a high separation rate per unit volume of process air. Preferably, the process air is then released again to a lower pressure level after the condensation step, in particular the pressure level is reduced to a value that corresponds to the pressure level of the incoming process air.

[0024] The volumetric flow rate also means the mass flow rate, in which case the density can be variable. However, for the description and comparison of the volumetric flow rates, it is preferable to state the volumetric flow rate as constant density. In this case, the volumetric flow rate is proportional to the mass flow rate. During the condensation process, it is generally expected that condensate may occur.

[0025] Preferred embodiments can be found in the dependent claims and in the description of the figures, whereby in the description of features no detailed distinction is always made between device aspects and method or use aspects.

[0026] In a preferred embodiment, at least one solvent is recovered using the method according to the invention, where the first condensate comprises a first solvent and the second condensate comprises a second solvent, in particular the first and / or second solvent comprises hydrocarbon compounds. In particular the first and second solvents may be the same or may differ in concentration or purity in the respective condensates. Both the first and second solvents are used in industrial processes, in particular for the production of lithium-ion batteries, and are transferred to the process air via a drying process. The solvent is at least partially separated again from the process air using the method according to the invention.

[0027] Therefore, the process air involved in industrial processes is preferably a carrier of organic solvents, which are gaseous, especially at process temperatures, and preferably contain at least one hydrocarbon compound. Solvents with gaseous organic components, also known as solvents with volatile organic compounds (VOC solvents), include, among others, NMP, TEP, EAA, or DMAc.

[0028] A method for recovering the solvent is also conceivable, in which the first condensate comprises a first solvent and the second condensate comprises a second solvent, in which the first and / or the second solvent comprises an inorganic solvent, which is suitable for dissolving an organic binder to form a paint or varnish. In particular, the inorganic solvent may also comprise water.

[0029] In a further preferred embodiment, the method according to the invention has a volume flow rate in the main and in the side stream, and at least a part of the process air after the first condensation step is branched in a side stream for treatment in the second condensation step, the volume flow rate branched in the side stream being in particular smaller than the volume flow rate present in the main stream after the branching. Preferably, the process air is split into at least two streams, for example a main stream and a side stream, after the first condensation step. Even in the case of branching into several side streams, the branched volume flow rate of all side streams combined is overall preferably smaller than the volume flow rate present in the main stream downstream of the branching. Thus, only a smaller part of the process air is branched from the main stream into a side stream and then treated by the second condensation step.

[0030] Treating only a small portion of the process air in the second condensation step has the advantage that less energy is required for cooling in the second condensation step than would be required to condense the majority of the process air in the second condensation step. Such a process operation allows for more flexible control of the amount of air condensed in the second condensation step according to economic criteria.

[0031] In a further preferred embodiment of the invention, at least a part of the process air is further treated in a first further treatment step after the first condensation step, which first further treatment step comprises a heat supply and / or a reduction in pressure and / or a second supply of air outside the main stream, in particular from the environment and / or from a sidestream, and at least a part of the process air after the first further treatment step is returned to an industrial process. Particularly preferably, the first further treatment is carried out in the main stream after the branching. Preferably, therefore, the process air in the main stream is further treated in the first further treatment step after the first condensation step. Thus, with respect to the main stream, the branching is located downstream of the first condensation step and upstream of the first further treatment step.

[0032] The first further treatment step may comprise a heat supply, a reduction in pressure and a second supply of ambient air or a second supply of process air from outside the main stream, for example from a side stream. It is also conceivable that a part of the process air upstream of the side stream is further treated in the first further treatment step after the first and second condensation steps. The process air in the side stream can therefore be passed through a second condensation step before being further treated in the first further treatment step. However, it is preferred that the process air is further treated in the first further treatment step after the first condensation step. The main stream can therefore only be passed to the first condensation step and not to the second condensation step. To that end, the main stream is preferably split after the first condensation step, with the main stream being returned and the side stream being fed to the second condensation step. Optionally, it is conceivable that the feed to the first further treatment step is from the main stream and from the side stream. The process air can therefore be combined from the main stream and from the side stream in the first further treatment step and further treated.

[0033] The first further treatment step may include any combination of the described further treatment means. Preferably, the process air may be first heated, with subsequent supply of ambient air to the process air before the process air is heated again. It is also conceivable to expand the process air in the first further treatment step, then heat the process air, and supply air from the (natural) environment before the process air is heated again. In an alternative embodiment, air from a side stream and from the (natural) environment is added to the process air in the first further treatment step. In a further embodiment, the process air is supplied only from a side stream, see the examples below for details. The further treatment of the process air in the first further treatment step may increase the absorption capacity of the process air for solvents from industrial processes.

[0034] If the drying capacity in an industrial process is increased, the method according to the invention can also provide an overall increase in conveying capacity in the short term by increasing the supply of ambient air to the first further treatment step.

[0035] In a further preferred embodiment of the invention, the first further treatment step is carried out after the branching. Preferably, the branching is carried out after the first condensation step, before a smaller part of the process air is branched off and fed as a side stream to the second condensation step. The branching is therefore carried out between the first condensation step and the first further treatment step with respect to the main stream, i.e. is located upstream of the first further treatment step. The second condensation step can therefore be carried out in a side stream. It is particularly preferred that the branching is carried out before the main stream is heated in the first further treatment step.

[0036] The part of the process air remaining in the mainstream after the branching can be further treated in a first further treatment step after the branching. Such a process treatment combines at least three important advantages with each other. Firstly, the process air branched off as a side stream is already cooled after the first condensation step, e.g. lower than after the first further treatment step, before the process air is further cooled by the second condensation step. Secondly, only a smaller part of the process air is diverted from the mainstream and treated in the second condensation step. The total volumetric flow rate of the branched off process air to be cooled is therefore smaller than the mainstream. Thirdly, the process air in the mainstream is reheated by the first further treatment step, e.g. for return to the industrial process, after only one condensation step, i.e. after the first condensation step. In other words, the combination of these at least three advantages results in a significantly more efficient overall process, since only a smaller volumetric flow is condensed at a lower temperature, while the remaining volume of the process air is cooled less and therefore does not have to be heated as much for return to the industrial process.

[0037] In a further preferred embodiment of the invention, at least a part of the process air is further treated in a second further treatment step after the second condensation step, which second further treatment step comprises heat supply, and / or decompression, and / or filtration, and / or a third condensation step, and / or adsorption. Preferably, the process air treated in the second condensation step is then heated in the second further treatment step and passed through a filter, for example an activated carbon filter, in order to further purify the process air from the solvent. The filter used can be selected so that the process air flowing therethrough complies with legal emission limits, in particular for emissions into the environment. In an alternative embodiment, the second further treatment step can comprise a third condensation step. The third condensation step can reach an even lower temperature than in the second condensation step. It is also conceivable to use a concentrator in the second further treatment step in order to further remove the solvent components from the process air by adsorption. In order to better adapt the second further treatment to the respective solvent components in the process air, if necessary, the third condensation step can also be combined with filtration or adsorption in the second further treatment step.

[0038] It is particularly preferred that the side stream is passed through a second condensation step and then further treated by a second further treatment step, however, typically at least a portion of the process air can be discharged to the environment as exhaust gas after the second further treatment step.

[0039] In a further preferred embodiment of the invention, a part of the process air is returned to the industrial process after the second further treatment step. The process air can be made available to a further process for further processing of the process air after the second further treatment step. In particular, the process air can be returned to the industrial process indirectly by preconditioning the process air for use in the industrial process, for example by further processing in a first further treatment step.

[0040] In a further preferred embodiment of the invention, at least a portion of the process air from the industrial process is fed into the main flow and filtered therein. During the industrial process, particles may be generated which are transported together during the introduction of the process air from the industrial process. To prevent such particles from entering the first condensation step, a filter can be used to filter the particles during the introduction of the process air into the main flow. In principle, the term "filtration" is understood to mean any other separation of particles. Therefore, electrostatic separators and / or cyclones are also conceivable. The filter is therefore preferably arranged upstream of the first condensation step. In particular, the filter can be a filter system which minimizes the pressure loss of the filter. The filters used are preferably adapted to the particle size, whereby different filter types can be used for different industrial processes.

[0041] In a further preferred embodiment of the present invention, the industrial process comprises a drying process, in particular the industrial process is part of the manufacturing process of lithium-ion batteries. In particular the industrial process may comprise a coating process, for example for coating electrodes and metal foils. The industrial process may also comprise the manufacture of membranes. However, the industrial process may also be part of the manufacturing process for the manufacture of wood products, in which case the solvent used is dried.

[0042] In a further preferred embodiment of the invention, the method according to the invention comprises recovering a first condensate during a first recovery process and / or recovering a second condensate during a second recovery process for return to the industrial process. During the first or second recovery process, preferably a first or second separated condensate is recovered. The recovery of the condensate can also be an intermediate storage before the solvent component of the condensate is returned to the industrial process. The return to the industrial process and reuse in this industrial process may impose certain technical requirements on the recovered condensate, which therefore needs to be purified in further process steps. The return to the industrial process therefore includes, if necessary, several treatment steps to achieve the properties, e.g. purity level, required for use in the industrial process.

[0043] The condensate separated from the process air may contain an aqueous solvent mixture. The treatment of the condensate for return to the industrial process may include, inter alia, distillation to separate the solvent components contained in the condensate and / or to increase the concentration of the respective solvent components. The distillation temperature for separating and / or concentrating the second condensate may therefore be different from the distillation temperature of the first condensate.

[0044] It is also contemplated that only the first condensate in the first recovery process may be recovered for return to the industrial process, and not the second condensate in the second recovery process. In certain circumstances, it may not be economically viable to repurify the second condensate for return to the industrial process, and therefore recovery and return of the second condensate may not be necessary.

[0045] In a further preferred embodiment of the invention, the method according to the invention comprises heat recovery in the first and / or second and / or third condensation steps. Preferably, the heat extracted in the respective condensation steps is recovered, for example by a heat exchanger or a heat pump. Preferably, the heat recovered in the process during heating is fed back to the process air, particularly preferably in the condenser, so that the heat transport path can be kept as short as possible to avoid losses. It is also conceivable to utilize the recovered heat in an industrial process, i.e. to add the heat recovered from the respective condensation steps to the industrial process.

[0046] In a further preferred embodiment of the invention, deicing is carried out in the second condensation step, with the supply of at least part of the process air to the second condensation step being temporarily interrupted and / or at least part of the process air being led away from the second condensation step and / or the supply of the process air to the second condensation step being splittable and the deicing being carried out in partial flows. It is conceivable in particular that the water vapor contained in the process air separates as solid particles (ice) in the second condensation step due to the low temperature and accumulates, for example, on the cooling fins of the heat exchanger. The adhesion of ice to the cooling fins or to the heat transfer surfaces generally impairs the heat transfer. Preferably, during deicing, the ice is removed from the heat transfer surfaces, so that the function of the heat exchanger can be fully restored. Deicing can be carried out by applying heat to melt the ice. The heat supply can then be effected, for example, by a fluid heating circuit (for example by an additional heating heat exchanger or by switching the working fluid circuit of the condenser heat exchanger, which serves as a cooling medium circuit, to an at least temporary supply of heated deicing medium) and / or by an electric heating element. In addition to or as an alternative to the addition of heat, it is also conceivable to carry out chemical deicing by the addition of a deicing fluid. The addition of a deicing fluid can be effected, for example, by spraying onto the heat transfer surface. In particular, the second condensing liquid can comprise a solvent that can be used as a deicing fluid for deicing.

[0047] A portion of the process air can be deflected and directed through the second condensing step during de-icing. Thus, the process air is diverted before entering the second condensing step and is, for example, supplied to a flow path downstream of the second condensing step. In particular, the supply of process air to the second condensing step can be temporarily interrupted during de-icing, so that the process air passes through the second condensing step only during de-icing. Thus, a continuous flow can be ensured during de-icing.

[0048] The supply of process air to the second condensation step can also be split into at least two, preferably at least two, alternating or alternating partial flows, which supply process air before the second condensation step during de-icing. The volume flow rate of one partial flow can in particular correspond to the volume flow rate of the sub-flow, so that the sub-flow can pass completely through one partial flow. By splitting the process air before the second condensation step, for example, one partial flow can be de-iced, while another partial flow can be treated in the second condensation step. The partial flows can thus be run in parallel, and both the de-icing and the second condensation step can be carried out in parallel, so that the separation of the second condensate can still take place in at least one partial flow during de-icing. This solution also ensures a continuous flow.

[0049] In particular, deicing can also be performed simultaneously with the second condensation step by deicing certain areas of the flow space, in which case deicing is performed locally, i.e. in spots, thereby allowing condensation to continue in other places in the flow space.

[0050] Deicing is understood to mean that the deicing process has at least started even if physical deicing, i.e., actual change of state from solid to liquid, has not yet occurred, and also includes a predetermined period or time interval following physical deicing to allow, for example, removal of water.

[0051] Also conceivable is a deicing with a predictive deicing process, in which relevant operating parameters are acquired and monitored, so that the deicing agent can be applied to the surface to be deiced in time and the ice accumulation process can be inhibited, so that the time interruption of the second condensation step for deicing can at least be reduced or even prevented altogether.

[0052] The invention further relates to an apparatus for treating process air from an industrial process, preferably for carrying out the above-mentioned method.

[0053] The invention is further based on the object of providing an advantageous device for treating process air from an industrial process for the recovery of condensate.

[0054] According to the invention, this problem is solved by an apparatus for treating process air from an industrial process, in particular an apparatus for carrying out the above-mentioned method, which comprises a main flow and a first condenser having a first cooling element and a first separator, in which the process air is cooled by the first cooling element and then passes through the first separator, a first condensate is separated from the process air and fed to a first recovery process. According to the invention, furthermore, a second condenser is provided, which has a second cooling element and a second separator and is connected downstream of the first condenser, in which the process air is cooled by the second cooling element and then passes through the second separator, a second condensate is separated from the process air and fed to a second recovery process.

[0055] Preferably, the main flow from the industrial process is fed to the first condenser. In so doing, the process air is preferably passed through the first cooling element. In particular, the first cooling element can be a heat exchanger with cooling fins, in particular a part of a heat pump or a cooling circuit, whereby heat is extracted from the process air and transferred to a cooling medium or heat exchange fluid. By cooling, condensate can be deposited on the heat transfer surfaces, for example the cooling fins, whereby the first condensate can be separated. A separator is preferably arranged downstream of the first cooling element, through which the process air can also pass. By cooling, aerosols can also be generated, which can also pass through the separator. Thereby, the condensate in the form of fine droplets can be intercepted by the separator. In particular, the separator can be an impact separator or a demister, for example with a wire mesh.

[0056] According to the invention, the second condenser is connected downstream of the first condenser, so that in this case the process air preferably passes through the first condenser before it is treated in the second condenser. In particular, in this device, a plurality of second condensers can be arranged downstream of the first condenser, so that the second condensers can be arranged in parallel with one another and at the same time in series with the first condenser.

[0057] Like the first condenser, the second condenser has a second cooling element and a second separator and is designed such that the process air is cooled therein such that the minimum temperature reached in the second condensation step is lower than the minimum temperature reached in the first condensation step. In particular, a coolant or heat exchanger fluid can be used for the second condenser that is chemically different from the first condenser and has a lower operating temperature than the coolant of the first condenser.

[0058] Particularly preferably, the first condenser and the second condenser each have a multi-stage cooling element, in which a number of heat sinks, in particular heat exchangers, can be arranged one after the other, through which the main flow can pass. Preferably, the process air is continuously cooled to the target temperature by the multi-stage cooling element. The separator can preferably be arranged downstream of the multi-stage cooling element. Optionally, the separator can also be arranged between the two heat sinks. To recover the first or second condensate, the condenser can have a recovery vessel and a condensate pump for delivering the separated first or second condensate to the respective recovery process.

[0059] In a preferred embodiment of the invention, the apparatus comprises a bypass device, in which at least a portion of the process air is branched off into a side stream downstream of the first separator in a branch, the bypass device preferably comprising a first control unit and / or a first valve and / or a fan for introducing at least a portion of the process air.

[0060] Preferably, a part of the process air is branched off from the main flow into a side stream in a branch after the first condensation step. In particular, the branching can be realized in a particularly simple manner in technical terms, for example by arranging a perforation or a through hole in the wall of the first flow path, so that the process air can escape from the main flow into the second flow path. However, preferably, a part of the process air is led off and branched off from the main flow into a side stream by a first valve and a fan of the bypass device. In this case, the first control unit can control the introduction of the process air into the side stream and thus can adjust the volume flow rate branched off into the side stream. In particular, the branching can be understood as tapping of the main flow. The bypass device, in particular the first valve, can be arranged in the first condenser. Particularly preferably, the first valve is arranged downstream of the first separator, whereby the process air in the first condenser can be branched off into a side stream downstream of the separator. In particular, the first valve may reduce or even completely stop the supply of process air to the side stream if diversion is not desired under certain operating conditions.

[0061] In a further preferred embodiment of the invention, the first cooling element comprises in particular a first heat exchanger for heat recovery during the first condensation step, at least a part of the process air is further treated after the first condensation step in a first condenser, which has a first heating element for heating the process air and, in particular, a first air heater downstream of the first condenser.

[0062] Preferably, a portion of the process air is further treated in a first condenser after the first condensation step, i.e. preferably downstream of the first cooling element and the first separator. Particularly preferably, the first cooling element comprises a first heat exchanger. Also preferably, the first heating element is a heat exchanger connected to the first heat exchanger. During further treatment in the first condenser, preferably the heat extracted from the process air in the first heat exchanger is used to reheat the process air via a heat pump or a cooling circuit. The cooling circuit preferably comprises a coolant, in particular a cooling liquid, for example water, which transfers heat from the cooling element to the heating element in order to heat the process air therein.

[0063] Particularly preferably, the first condenser has at least two cooling stages with respective cooling elements, whereby the cooling elements have respective coolants. Preferably, each cooling stage has a respective cooling circuit with a coolant, so that the cooling capacities of the different cooling stages can be adjusted individually.

[0064] Particularly preferably, each cooling stage has its own coolant, in particular in the case of several cooling stages in one condensation step, i.e. the first cooling stage has a first coolant and the second cooling stage has a second coolant. Optionally, the cooling stages can each have an individual cooling circuit. The heat extracted from the process air during cooling can then be added to the process air in a further treatment step. Heat transfer can therefore take place between the condensation step and the further treatment step by means of the coolant, whereby thermal energy from the process air is transferred from the condensation step to the further treatment step. The coolant, in particular the cooling liquid, can therefore ensure a high cooling capacity in the cooling stage. In particular, the cooling capacity in an air-water heat exchanger can be higher than in an air-air heat exchanger. Preferably, a coolant is already used in the first cooling stage for cooling the process air, whereby the heat extracted from the process air in the first cooling stage is added to the process air in a further treatment step. The heat transfer can be realized simply by pumping the coolant. Optionally, the heat transfer can also be realized by means of a heat pump.

[0065] Optionally, but particularly preferably, the process air is further treated in the main stream in a first condenser downstream of the branch. Regardless of whether heat is recovered during the first condensation step, it is also optionally possible to arrange a heating element operated by an external heatable flow (Strom) as the first heating element in the first condenser. Optionally, the first heat exchanger can return the recovered heat to the process air outside the first condenser. In particular, the recovered heat can optionally be supplied to an industrial process.

[0066] Particularly preferably, the device comprises a first air heater arranged downstream of the first condenser, preferably downstream of the air inlet for supplying the main stream of external air. Preferably, the first air heater can improve the drying properties of the process air for the industrial process, for example by further heating the process air and reducing the relative humidity of the process air. The preferred arrangement of the first air heater downstream of the first condensation step has the advantage that a significant proportion of the solvent can already be condensed out of the process air during the first condensation step, before the first air heater heats the process air.

[0067] In a further preferred embodiment of the invention, at least a part of the process air is directed in a side stream to the second condenser during branching upstream of the first heating element. In particular, the branching takes place in the first condenser before the process air is reheated by the first heating element. Preferably, the branching can be arranged in the first condenser between the first separator and the first heating element, so that a part of the process air is already cooled by the first cooling element and branched off in the first condenser after the first condensate has been separated by the first separator and before reaching the first heating element.

[0068] In a further preferred embodiment of the invention, the second cooling element in particular comprises a second heat exchanger for heat recovery during the second condensation step, and at least a portion of the process air is further treated after the second condensation step in a second condenser, which second condenser comprises a second heating element for heating the process air.

[0069] Preferably, a portion of the process air is further treated after the second condensation step in a second condenser, i.e. preferably downstream of the second cooling element and the second separator. Particularly preferably, the second cooling element comprises a second heat exchanger. Also preferably, the second heating element is a heat exchanger connected to the second heat exchanger. During further treatment in the second condenser, particularly preferably, the heat extracted from the process air in the second heat exchanger reheats the process air via a heat pump by means of the second heating element. In particular, the heat exchanger of the heat pump can be arranged inside or outside the second condenser. The second heating element arranged in the second condenser can also be a current-driven heating element. Optionally, the second heat exchanger can return the recovered heat to the process air outside the second condenser. In particular, the recovered heat can optionally be supplied to an industrial process.

[0070] Preferably, the process air in the second condenser is conditioned so that it is suitable for further processing in the second further processing device. For example, it may be necessary for the process air to be conditioned to a certain temperature and / or a certain pressure, so that the process carried out in the second further processing device, e.g. adsorption, can be carried out as effectively as possible.

[0071] In a further preferred embodiment of the invention, after the second condensation step a second further treatment device is arranged, by which the process air is further treated, which second further treatment device comprises a filter and / or a third condenser and / or a concentrator.

[0072] Particularly preferably, the second further treatment device has an activated carbon filter, which can remove, for example, further solvent components still contained in the process air in order to comply with predefined legal emission limits when discharged into the environment.

[0073] In particular, however, the second further treatment device may optionally have a third condenser for treating the process air in a third condensation step. In this case, the third condenser may be connected in series with the second condenser, so that the process air preferably always passes through the second condenser before it is treated in the third condenser. It is also conceivable to arrange several third condensers in parallel.

[0074] Optionally, the second further treatment device comprises a concentrator capable of removing solvent components from the process air by adsorption.

[0075] The second further processing device may, in a further embodiment, comprise any combination of a filter, a condenser, or a concentrator. For example, the second further processing device may be used for the removal of different solvent components, and it is envisaged that a combination of a filter and a condenser or concentrator may be useful.

[0076] In a further preferred embodiment of the invention, the device according to the invention comprises a first condensate collector and a second condensate collector, wherein the first condensate is collected during a first recovery process for return to the industrial process and the second condensate is collected during a second recovery process for return to the industrial process.

[0077] The first or second condensate collectors may each be an intermediate storage tank, reservoir, or vessel that may be located within the respective condenser or may be external to the respective condenser. Each condensate collector differs from a pipe in that the condensate collector has a primary purpose of collection, not transportation.

[0078] In particular, each condensate collector may be part of an apparatus for repurifying each condensate for return to the industrial process, and in particular, such an apparatus may be used for distillation to concentrate the solvent components of the condensate for the industrial process.

[0079] In a further preferred embodiment of the invention, the second condenser comprises a de-icing device. According to the invention, the process air in the second condenser can be cooled to a temperature at which ice deposits can occur on the cooling fins of the second cooling element or in the second separator. Ice deposits are undesirable, since they can significantly impair the thermal conductivity of the cooling fins or the capacity of the second separator. The de-icing device ensures that ice deposits are removed from the second condenser after a predefined operating interval. In particular, the de-icing device preferably comprises a heater, which can directly heat the parts to be de-iced or indirectly heat the process air so that the accumulated ice can melt from the parts. Optionally, a de-icing agent is provided on the parts to be de-iced, whereby ice is removed from the corresponding surfaces. In particular, de-icing can be performed in parts of the second condenser during sustained condensation, i.e. locally or partially. Deicing devices with a predictive deicing process are also conceivable, whereby the relevant operating parameters are acquired and monitored, so that the deicing agent can be applied to the surface to be deiced in a timely manner, so that ice build-up can be suppressed from the very beginning, in order to ensure the functionality of the second condenser at all times. Optionally, the deicing device can have a heater for simultaneously heating the parts to be deiced and applying the deicing agent. Such a combination of deicing devices can advantageously accelerate deicing.

[0080] As mentioned above, the second condensation step may comprise at least two parallel partial flows with corresponding condensers arranged in parallel, so that during de-icing in one condenser, the process air supply can be at least partially, preferably essentially completely, diverted to the other condenser, whereby the second condensation step is carried out continuously and does not have to be interrupted.

[0081] In particular, the de-icing device can use a signal supply device so that the supply of at least a part of the process air to the second condenser can be temporarily interrupted. Preferably, the de-icing device can communicate with a control unit, e.g. a first control unit, whereby a valve for directing the process air, e.g. the first valve, can be controlled accordingly.

[0082] In a further preferred embodiment of the invention, the industrial process comprises coating a conductive carrier material, in particular a conductive film material, with a solvent-containing mixture as a coating and drying after application of the coating to the carrier material, in which solvent-containing process air is generated, which is fed to the device.

[0083] In the following, the invention will be explained in more detail with reference to some embodiments, without making any detailed distinction between the different categories of the claims. Moreover, it is clear that the solution according to the invention can be applied in a variety of different industrial processes. [Brief description of the drawings]

[0084] [Figure 1] FIG. 1 is a schematic diagram of a method according to the invention for treating process air from an industrial process for drying electrode coatings. [Diagram 2] FIG. 1 is a schematic diagram of an apparatus according to the present invention for treating process air from an industrial process for drying electrode coatings. [Diagram 3] FIG. 2 is a schematic diagram of an alternative apparatus according to the invention using a method according to the invention for treating process air from an industrial process. [Figure 4] FIG. 2 is a schematic diagram of a further alternative apparatus according to the invention using a method according to the invention for treating process air from an industrial process. [Diagram 5] FIG. 3 is a modification of FIG. 2 with an alternative arrangement for treating process air from a side stream. [Figure 6] FIG. 3 is a modification of FIG. 2 with a further alternative arrangement for treating process air from a side stream. [Figure 7] FIG. 3 is a schematic diagram of a cross section of a partial region of the heat exchanger as an optional design of the second condenser from FIG. 2 . [Figure 8] FIG. 3 is a further modification of FIG. 2 having auxiliary piping. [Figure 9] FIG. 9 shows an alternative embodiment according to FIG. 8 having an air-to-air heat exchanger. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0085] In the manufacture of electrodes for lithium-ion batteries, for example, a wet coating in the form of a slurry or paste can be applied to a support. According to the invention, this is carried out during an industrial process carried out on an industrial scale in an industrial installation 1, 1a. In this case, a preferably conductive flat substrate, in particular a conductive or metallic film, is used as the support. The wet coating preferably has a component consisting of a fine powder mixed with a binder. Typically, a polymer is used as the binder, which may be water-soluble. If necessary, the binder is dissolved in an organic solvent, for example NMP, TEP, EAA, acetone, various alcohols or similar industrial solvents, and, if necessary, mixtures thereof. Such a solvent is suitable for dissolving the organic binder in order to obtain a layer-forming fluid, in particular a paste or liquid. Such a liquid can be applied to at least one side of the support material to form a coating. In such a case, the wet coating is applied continuously or discontinuously to the moving support and dried in an oven or dryer. In the course of drying, the solvent is usually removed, whereby the applied coating solidifies. In a typical case where a film is coated on both sides, a first coating is applied successively to a moving support and dried in an oven or dryer, and then a second wet coating is applied and dried in a second drying step.

[0086] In a particularly preferred embodiment for the manufacture of battery electrodes, the wet slurry is applied to both sides of a support and then dried in an oven or dryer. This procedure is called double-sided simultaneous coating and drying. For the manufacture of lithium-ion electrodes, this procedure is particularly advantageous in terms of improving productivity, since only one drying step is required after the wet coating slurry is applied to both sides.

[0087] According to the invention, volatile organic compounds (VOCs) are released during the drying process, particularly in a dryer or oven, essentially in the form of vapor into the oven atmosphere and thus into the process air, and are condensed together with water and other potential impurities in a condenser to recover the solvent (e.g. NMP, TEP, EAA, DMAc). The process air then passes through a device that separates fine droplets (demister, droplet separator). In most drying processes, at least a portion of the air leaving the condensation process is released into the atmosphere, while the remaining air can be returned to the dryer. For many solvents, the concentrations released from the condenser far exceed the permissible limits for release into the atmosphere. Moreover, such solvent recovery is cost-effective and desirable. Therefore, additional downstream purification equipment is usually required due to emission limitations in order to reduce the VOC concentrations to permissible values. VOC removal processes include thermal (catalytic and purely thermal) oxidation processes, carbon adsorption, and adsorption using various adsorption media such as zeolites, activated carbon, etc.

[0088] Figure 1 shows a schematic diagram of an example of a method according to the invention for treating process air from an industrial process for manufacturing lithium-ion batteries. In the method shown in Figure 1, an electrode coating process 1a is carried out, using a solvent preferably consisting of a combination of TEP and EAA. Process air is used to dry the electrode coating, which comprises a moist TEP / EAA solvent.

[0089] According to the method according to the invention, the process air is led in the main flow 5 to a first condensation step 41, in which the process air is filtered. The filtration step 4a thereby serves to separate the process air from the coarse particles generated during the electrode coating process 1a. In the first condensation step 41, the process air is continuously cooled down to 15°C from 120°C at the entry to the first condensation step 41. The first condensate 16 is thereby separated from the process air and fed to a first recovery step 42. In the first condensation step, the process air can be purified so that the concentration of TEP / EAA solvent in the process air is reduced from typically about 4000 ppm at the inlet to the first condensation step to, for example, about 300 ppm at the outlet (i.e. reduced by a factor of 10 or more). In the recovery step 42, the first condensate 16 is recovered and further treated, preferably by distillation and condensate re-purification processes, not shown. In so doing, the first condensate 16, for example comprising TEP / EAA solvent, is concentrated to form a first concentrated condensate 16a, optionally separated into different solvent components (TEP and EAA), and then returned to the electrode coating process 1a.

[0090] After the process air in the mainstream has been treated by the first condensation step 41, a side stream 31 is branched off from the mainstream via a branch 44 and led to a second condensation step 51. The volume flow branched off to the side stream 31 typically corresponds to approximately 10% of the volume flow remaining in the mainstream 5 after the branch 44, which remaining volume flow is led to a first further treatment step 45.

[0091] In the main flow 5, the process air is, after the branch 44, conditioned for the electrode coating process 1a in a first further treatment step 45 by first heating it, then supplementing it, if necessary, with air from the environment and then (at least optionally) heating it. After the first further treatment step 45, the process air is returned to the electrode coating process 1a in the main flow 5. The main flow 5 is then also called recirculation flow or "make-up air".

[0092] After split 44, the split process air in the side stream 31 is led to a second condensation step 51. The split process air preferably has a temperature of 15° C. on entering the second condensation step 51. In this step, the process air is continuously cooled, for example to −20° C., whereby a second condensate 17 is separated from the process air and fed to a second recovery step 52. In the second condensation step, the process air can be purified so as to reduce the concentration of TEP / EAA solvent in the process air from typically about 300 ppm on entering the second condensation step to typically about 50 ppm on leaving the second condensation step.

[0093] In particular, ice build-up can occur due to the low temperature of the process air in the second condensation stage 51. To combat ice build-up, de-icing can be carried out after certain operating intervals of the second condensation stage. During de-icing, the supply of process air from the side stream 31 to the second condensation stage 51 is temporarily interrupted.

[0094] During the recovery process 52, the second condensate 17 is recovered and subjected to further distillation and condensate repurification processes (not shown) in which the second condensate 17 is purified into a second concentrated condensate 17a, which contains in particular the TEP / EAA solvent, and is separated into the respective solvent components (TEP and EAA) and returned to the electrode coating process 1a.

[0095] The process air in the side stream 31 is treated after the second condensation step 51 in a second further treatment step 54. The process air is first tempered to 15° C., then filtered and finally discharged into the environment via a discharge step 55. Filtration in the second further treatment step 54 ensures that solvent components in the process air are removed, so that legal emission limits can be met.

[0096] Figure 2 shows a schematic example of an apparatus according to the invention for carrying out the method according to figure 1. Reference number 1 shows an exemplary electrode coating apparatus in which electrodes for the production of lithium-ion batteries are coated, using the above-mentioned solvent consisting of a mixture of TEP and EAA. Process air from the electrode coating process 1a is sent by a blower 61 in the main flow 5 to the first condenser 2 and is preferably passed through a filter 4 before entering the first condenser 2. The temperature of the process air is typically about 120°C on entering the first condenser 2 and is continuously cooled to 15°C in the first cooling element 6. The first cooling element 6 optionally comprises a three-stage heat exchanger 6a in which heat is extracted from the process air. In the first stage of the heat exchanger 6a the process air is cooled from an entering temperature of 120°C to typically about 60°C, in the second stage typically to about 40°C and in the third stage typically to about 15°C. The heat extracted in the first stage is transferred via a heat pump 15 to a first heating element 18 formed as a heat exchanger. The first heating element 18 is used to return the heat extracted in the heat exchanger 6a to the process air of the main stream 5. The heat extracted in the second and third stages can furthermore optionally be supplied via a separate heat pump to a further process not shown, e.g. a thermal coupling in an electrode coating process 1a.

[0097] The heat exchanger 6a has a heat sink with vertical cooling fins at each stage, through which the process air is guided. As a result of the cooling, a first condensate 16 is formed on the surface of the cooling fins, which is guided by gravity to a collection vessel located below the first cooling element 6. As a result of the cooling in the first cooling element 6, aerosol formation can occur, which results in the appearance of aerosols, which are transported with the main flow through the first condenser. For this reason, it is preferable to arrange a first separator 7 downstream of the first cooling element 6, which is formed as a wire mesh "demister" for separating fine droplets or as an impact separator. The process air flows through the first separator 7, which results in the formation of a first condensate 16, which is guided by gravity to a collection vessel located below the first cooling element 6.

[0098] The separated first condensate 16 includes a first solvent 16a, which may have a mixture of TEP and EAA and various by-products with similar condensation properties. The first condensate 16 is pumped from the collection vessel to a first condensate collector 13 external to the first condenser 2 and distilled in a condensate re-purification unit 14a for return to the electrode coating process 1a. In the process, the first condensate 16 is separated and concentrated into its respective solvent components (TEP and EAA) in the condensate re-purification unit 14a.

[0099] Downstream of the first separator 7, a part of the process air is branched off from the main flow 5 via the first valve 9 of the bypass device and diverted in a side stream 31 to the second condenser 3. The second cooling element 32 is an essential component of the second condenser 3 and has a two-stage heat exchanger 32a which extracts heat from the process air. The process air is cooled from 15° C. to −5° C. in the first stage and to −20° C. in the second stage. The heat extracted in the first stage is transferred via a heat pump 34 to the second heating element 19 formed as a heat exchanger. The previously extracted heat is at least partially added to the process air in the side stream 31 via the second heating element 19. The heat extracted in the second stage is added, if necessary, via another heat pump to a further process, not shown. The separation of the second condensate 17 as well as the configuration of the second heat exchanger 32a and the second separator 33 (demister) are preferably performed similarly to the first condenser 2. The second condensate has a second solvent 17a, which may preferably have the same composition (TEP and EAA) as the first solvent 16a. Similar to the first condensate 16, the second condensate 17 is also pumped out of the collection vessel to a second condensate collector 37 outside the second condenser 3 and distilled in a condensate re-purification unit 14b for return to the electrode coating process 1a. In this condensate re-purification unit 14b, the second condensate 17 is separated and concentrated into its respective solvent components (TEP and EAA).

[0100] The second condenser 3 also preferably comprises a de-icing device 38, which comprises a heater (not shown) in the second cooling element, which is activated by an electric current. The de-icing device 38 can further heat the separated condensate 17 with the solvent 17a of the TEP / EAA mixture, which can be used as a de-icing means in the second cooling element 32. The de-icing device 38 can alternatively comprise a thermal connection to the heat exchanger of the second condenser, which heats a given heat transfer surface of the second cooling element 32 in order to remove ice from the heat transfer surface. In order to interrupt the supply of process air before the second condenser is de-iced by the de-icing device 38, a signal is sent to the first control unit 10, which closes the first valve 9.

[0101] Downstream of the second separator 33, the process air of the side stream 31 is heated to 10° C. by means of the second heating element 19 by means of the heat recovered from the second heat exchanger 32a. Downstream of the second condenser 3 is arranged a second air heater 35, via which the process air is subsequently further heated to 15° C. before it is led to a second further treatment device 39. In the second further treatment device 39, the process air is filtered via an activated carbon filter 36 before finally being discharged through the air outlet 21 to the environment 11.

[0102] Downstream of the separator 7, the process air in the main flow 5 is heated by a first heating element 18 to between 15°C and 60°C before the process air leaves the first condenser 2 and is directed to the first air heater 12 for further conditioning.

[0103] The second and third valves 23a, 23b are controlled by a second control unit 22 which is capable of communicating with the first control unit 10. The second valve 23a is intended to regulate the amount of air from the environment 11 through the air inlet 20 and thereby the amount of air in the main flow 5. In normal operation, the air inlet 20 can be kept closed and the air inlets can be arranged as so-called "web-slots" in the electrode coating device 1. Thereby, the amount of air supplied to the electrode coating process 1a via the web-slots corresponds to the amount of air diverted to the side flow 31.

[0104] The air supplied from the environment 11 and the process air from the condenser 2 are led in the main flow 5 to a first air heater 12, in which the air for the electrode coating process 1a is heated and finally supplied again to the electrode coating device 1.

[0105] Figure 3 shows a schematic representation of an alternative embodiment of the device according to the invention, which is substantially similar to the embodiment shown in figure 2 and is therefore described with reference to the above description. In contrast to the embodiment shown in figure 2, in this embodiment a return line 31 is provided, via which the process air is returned to the main flow 5 via the air inlet 20 in a side stream 31 downstream of the second condenser 3. In this alternative embodiment the process air is therefore not released into the environment as exhaust air but is used again in the industrial process.

[0106] Fig. 4 shows a schematic diagram of a further alternative embodiment of the device according to the invention. This alternative embodiment is substantially similar to the embodiment according to Fig. 2 and is therefore described with reference to the above description. In contrast to the embodiment according to Fig. 2, the second further treatment device further comprises, in addition to the activated carbon filter 36, a concentrator 43 with zeolite as adsorbent. The process air of the side stream 31 is typically temperature-regulated to about 25°C downstream of the second condenser 3 and is led to the concentrator 43. In the concentrator 43, the second solvent 17a, which comprises NMP, is also adsorbed and removed. In the process, the process air is purified so that the concentration of the solvent in the process air can be reduced from typically about 50 ppm when entering the concentrator 43 to about 10 ppm when leaving the concentrator 43.

[0107] FIG. 5 shows a variant of the embodiment according to FIG. 2 with an alternative arrangement for treating the process air from the side stream 31. For the sake of clarity, elements identical to the embodiment shown in FIG. 2 have been omitted. The side stream 31 can be split into two partial streams 31a, 31b, each of which is led to the second condenser 3 or to the parallel condenser 3a. The parallel condenser 3a is preferably of identical construction to the second condenser 3 and is arranged in parallel with it. The respective partial flows through the second condenser 3 and the parallel condenser 3a can be regulated by the fourth and fifth valves 23c, 23d. In a complementary or alternative embodiment, the side stream 31 can be split into two partial flows 31a, 31b by an alternating valve, not shown. The fifth valve 23d normally remains closed and is opened when the second condenser 3 is deiced. The second condenser 3 is de-iced in the same way as described above for the embodiment according to Fig. 2, by means of the cooling element 32 or an electric heating element arranged in the heat exchanger 32a. As a complement or alternative to this, heat can be coupled to the heat exchanger 32a for de-icing (see above description of Fig. 2). Preferably, the cooling by the cooling element 32 can be temporarily interrupted during de-icing in order to give priority to a natural heat input from outside.

[0108] The parallel condenser 3a also provides some operational redundancy, for example, and can be used when the second condenser 3 is being serviced. The parallel condenser 3a is (at least optionally) de-iced in a similar or identical manner to the de-icing of the second condenser 3, but is preferably de-iced in a staggered manner relative to the de-icing of the second condenser 3.

[0109] Figure 6 shows a further variant of the embodiment of Figure 2 with an alternative arrangement for treating the process air from the side stream 31. During de-icing of the second condenser 3, the fourth valve 23c is closed and the supply of process air to the second condenser 3 can be interrupted. At the same time, the sixth valve 23e is opened, whereby the process air is sent around the second condenser 3 via the bypass line 40. Optionally, the process air is sent via the bypass line 40 to a gas storage tank (not shown) and temporarily stored there. At a later point in time, the bypass line 40 is closed again and the process air is returned via the second condenser 3 (including, if necessary, the amount of process air stored in the meantime). Thereby, the predetermined flow rate of the side stream is maintained even if the supply to the second condenser 3 is temporarily interrupted.

[0110] FIG. 7 shows a schematic cross-section of a partial area of ​​the heat exchanger 32a as an optional implementation of the second condenser from FIG. 2. The heat exchanger 32a has a number of cooling fins in fin packs 72a, 72b, 72c, which are arranged individually in a housing 71. The de-icing device 38 has an electric heating element 74, which is assigned to each surface of the cooling fins. In normal cooling operation, the electric heating element 74 remains switched off while the coolant led in the coolant tube 73 flows through the respective fin pack 72a, 72b, 72c. The heat of the process air flowing past the cooling fins is then transferred to the coolant. The second condensate 17 accumulates on the surface of the cooling fins as a result of condensation and is then led by gravity to a collection container 75. For example, the flow of the coolant through the fin pack 72a, i.e. the cooling of the fin pack 72a, can be temporarily interrupted. In this case, the electric heating element 74 can be switched on to melt the ice away while the fin packs 72b, 72c continue to operate to cool the process air, thereby allowing de-icing to occur locally, i.e. only at the fin pack 72a of the heat exchanger 32a, while the process air can continue to condense elsewhere along the fin packs 72b, 72c.

[0111] Figure 8 shows a further variant of the embodiment according to figure 2 with an auxiliary line 46. In this case, the auxiliary line 46 is arranged downstream of the branch arranged upstream of the first heating element 18 (alternatively 18a). After the process air is heated by the heating element 18a, a part of the heated process air is branched off into the side stream 31 and fed to the process air in the side stream 31. The amount of process air branched off via the auxiliary line 46 is regulated via the auxiliary line valve 9a. In particular, the supply of heated process air can reduce the relative humidity of the process air in the side stream 31, making it easier to handle. For example, unwanted condensation in the side stream piping can be prevented.

[0112] FIG. 9 shows an alternative implementation of the embodiment shown in FIG. 8 with an air-air heat exchanger, here shown as a cross-flow heat exchanger 24. The cross-flow heat exchanger 24 is assigned to the main flow 5, in which case the process air removed from the electrode coating device is led to the cross-flow heat exchanger 24 before entering the first condenser 2. This allows thermal energy to be extracted from the process air before it is led to the first condenser 2 and a certain pre-cooling can be performed. On the other hand, the process air is led to the cross-flow heat exchanger 24 downstream of the first condenser 2. The thermal energy thus extracted from the process air is then fed back to the process air before it is led to the electrode coating device 1. With the cross-flow heat exchanger 24, the energy efficiency of the device 60 is further improved, for example by less thermal energy being supplied to the process air by the first air heater 12 to reach a similar temperature level. At the same time, pre-cooling using the cross-flow heat exchanger 24 means that less cooling capacity must be supplied to the first condenser 2 to cool the process air to the required temperature level.

Claims

1. A method for treating process air from an industrial process having a mainstream (5), wherein at least a portion of said process air is treated by the following method steps: a first condensation step (41) in which a first condensate (16) is separated from the process air and fed to a first recovery process (42); a second condensation step (51) following the first condensation step (41), in which a second condensate (17) is separated from the process air and fed to a second recovery process (53), A method according to claim 1, wherein the minimum process air temperature reached during said second condensation step (51) is lower than the minimum process air temperature reached during said first condensation step (41).

2. 2. The method according to claim 1 for the recovery of at least one solvent (16a, 17a), the first condensate (16) comprises a first solvent (16a) and the second condensate (17) comprises a second solvent (17a); In particular, the first and / or second solvent (16a, 17a) comprises a hydrocarbon compound.

3. having respective volumetric flow rates in the main stream (5) and the minor stream (31), branching at least a portion of the process air after the first condensation step (41) in a branch (44) into the substream (31) for treatment in the second condensation step (51); 3. The method according to claim 1 or 2, wherein the volume flow branched off in the secondary flow (31) is in particular smaller than the volume flow present in the primary flow (5) after the branch (44).

4. further treating at least a portion of the process air after the first condensation step (41) in a first further treatment step (45); said first further treatment step (45) comprising the supply of heat and / or the reduction of pressure and / or a second supply of air external to the main stream (5), in particular from the environment (11) and / or from a side stream (31), The method according to any one of claims 1 to 3, wherein at least a portion of the process air is returned after the first further treatment step (45), in particular to the industrial process (1a).

5. A first further processing step (45) is carried out after the branch (44), The method according to any one of claims 1 to 4, in particular in which a heat supply is provided in the first further treatment step.

6. 6. The method according to any one of the preceding claims, wherein at least a part of the process air is further treated in a second further treatment step (54) after the second condensation step (51), this second further treatment step (54) comprising the supply of heat, and / or reduction in pressure, and / or filtration, and / or a third condensation step, and / or adsorption.

7. 7. The method according to claim 6, wherein at least a portion of the process air is fed to the environment (11) after the second further treatment step (54).

8. 7. The method according to claim 6, wherein at least a portion of the process air is returned, in particular to the industrial process (1a), after the second further treatment step (54).

9. The method according to any one of the preceding claims, wherein at least a portion of the process air from the industrial process (1a) is led into the main flow (5) and is filtered therein.

10. The method according to any one of claims 1 to 9, wherein the industrial process (1a) comprises a drying process.

11. The method according to any one of claims 1 to 10, comprising recovering the first condensate (16) during the first recovery process (42) and / or recovering the second condensate (17) during the second recovery process (52), in particular for return to the industrial process (1 a).

12. The method according to any one of the preceding claims, wherein the method comprises heat recovery during the first and / or second and / or third condensation steps (41, 51).

13. De-icing is carried out in the second condensation step (51), temporarily interrupting the supply of at least a portion of the process air to the second condensation step; and / or directing at least a portion of the process air away from a second condensation step; and / or 13. The method according to any one of the preceding claims, wherein the process air supply to the second condensation step is splittable and the de-icing is carried out in a partial flow.

14. An apparatus (60) for treating process air from an industrial process (1a), in particular for carrying out the method according to any one of claims 1 to 13, Mainstream (5) and a first condenser (2) having a first cooling element (6) and a first separator (7), in which the process air is cooled by the first cooling element (6) and then passes through the first separator (7), and a first condensate (16) is separated from the process air and fed to a first recovery process (43); a second condenser (3) connected downstream of the first condenser (2), comprising a second cooling element (32) and a second separator (33), in which the process air is cooled by the second cooling element (32) and then passes through the second separator (33), and a second condensate (17) is separated from the process air and fed to a second recovery process (53); An apparatus (60).

15. An apparatus (60) for carrying out the method according to any one of claims 1 to 13, comprising: A bypass device (8), at least a portion of the process air is branched off into a substream (31) downstream of the first separator (7) in a branch (44); 15. Apparatus (60) according to claim 14, wherein the diversion device (8) preferably comprises a first control unit (10) and / or a first valve (9) and / or a fan for introducing at least a portion of the process air.

16. said first cooling element (6) in particular comprising a first heat exchanger (6a) for heat recovery during said first condensation step (41), at least a portion of the process air is further treated in the first condenser (2) after the first condensation step (41); the first condenser (2) having a first heating element (18) for heating the process air, 16. Apparatus (60) according to claim 14 or 15, characterized in that downstream of the first condenser there is arranged in particular a first air heater (12).

17. 17. Apparatus (60) according to claims 14 and 16, wherein at least a portion of the process air is led in a subsidiary flow (31) to the second condenser (3) in a branch (44), upstream of the first heating element (18).

18. said second cooling element (6) in particular comprising a second heat exchanger (32a) for heat recovery during the second condensation step (51), Apparatus (60) according to any one of claims 14 to 17, wherein at least a portion of the process air is further treated in the second condenser (3) after the second condensation step (51), the second condenser (3) comprising a second heating element (19) for heating the process air.

19. a second further treatment device (39) is disposed after the second condensation step, The process air is further treated by the second further treatment device (39), which comprises: A filter (36), and / or a third condenser; And / or the device (60) according to any one of claims 14 to 18, further comprising a concentrator.

20. a first condensate collector (13) in which the first condensate (16) is recovered during the first recovery process (43) for return to the industrial process (1a); a second condensate collector (37) in which the second condensate (17) is recovered during the second recovery process (53) for return to the industrial process (1a); The apparatus (60) of any one of claims 14 to 19, comprising:

21. The device (60) according to any one of claims 14 to 20, wherein the second condenser (3) comprises a de-icing device (38).

22. The industrial process (1a) comprises: Coating a conductive carrier material, in particular a conductive film material, with a mixture comprising a solvent as a coating film; drying said coating film after application to said carrier material to produce solvent-laden process air which is fed to said device (60); An apparatus (60) according to any one of claims 14 to 21, characterized in that it comprises:

Images