EP2829403B1 - Device for applying substance mixtures having a constant concentration onto a material web and method of cleaning waste gases from the device - Google Patents

Description

The invention relates to a device for applying in each case at least one organic solvent-containing mixtures to a material web. The invention further relates to a method for providing a portion of an exhaust gas stream for a catalytic oxidation unit integrated in the apparatus. Device and method are generically from the DE 103 57 559 A1 known.

Become solvent-containing mixtures, such as paints, coatings or plastic mixtures, applied to surfaces of materials, it is then usually to evaporation of the solvent, the z. B. to solve paint or paint components or act as a plasticizer. The evaporation rate of the solvent depends on various conditions, such as the type of solvent or solvent (s), the solvent temperature, the ambient temperatures, the ventilation intensity or the ambient pressures from.

When printing or coating (henceforth summarized as: application) of materials, especially webs, z. B. of rolls of packaging materials, paper, films, sheets, plastics, composite materials such as multilayer films, chipboard, glued wood panels or sheets of glass or natural materials such as wood, the at least one solvent serves, inter alia, to keep the mixture sufficiently liquid to a To allow trouble-free processing and to achieve good adhesion of the mixture on the surface of the material.

Solvent-containing mixtures are applied to webs of material, for example, printed, a concentration of the solvent in the applied mixtures must be quickly lowered so far that overprinting or winding of the web is possible without causing blurring of the applied mixture. The reduction of the solvent concentration is usually carried out by drying the applied substance mixture by the supply of air streams or by irradiation, for example with infrared radiation. In order to allow rapid drying, highly volatile organic compounds (VOC = very volatile organic compounds; DIN EN ISO 16000-6; California specification section 01350; RiLi 1993/13 / EC; but especially RiLi 2004/42 / EC). The drying may include, in addition to a reduction in the solvent concentration contained in the applied mixture, a decomposition or conversion of substances of the mixture. The drying parameters are adjusted to the desired printing speed.

The air used for drying is loaded after drying with solvent and / or decomposition products and is discharged as exhaust gas flow from the web. This results in two requirements. First, it must be prevented that at any area of the device, the solvent concentration in the exhaust gas flow reaches values at which there is an inadmissibly high risk of explosion of the exhaust gas flow. Technically, the indication of a lower explosion limit (LEL) and an upper explosion limit (LEL) in grams of solvent per cubic meter indicates an impermissible value range of the solvent concentration. Secondly, the solvents must be suitably treated so that the exhaust gas flow can be released to the environment in compliance with environmental and occupational safety regulations. Cleaning is usually carried out by a thermal reaction of the solvents contained in the exhaust gas stream or in a portion of the exhaust gas stream. A thermal reaction, usually a (post) combustion, is an oxidative process, which is preferably carried out in the presence of a suitable catalyst. Important here is the relationship between oxygen and pollutant. The oxidizable amount of pollutants is determined by the amount of oxygen available. For noble metal catalysts, there must be at least an excess of oxygen of 2%. If metal oxide compounds are used, the excess is at least 12%. With a direct recirculation of the exhaust gas from a catalytic oxidation unit, this means at 12 g / m ^{3 of} ethanol as a pollutant, that at the same total volume flow maximum 80% of the exhaust gas can be recycled and reused.

From the prior art, for example from the DE 103 57 559 A1 , It is known that the solvent-containing exhaust gas stream can be purified by means of a catalytic post-combustion system, which can be integrated in a flexographic printing machine. In the catalytic afterburning heat energy is released, which is available for heating the exhaust gas before it is fed to the catalytic afterburner (henceforth: catalytic oxidation unit). By heating the exhaust gas stream, an improved efficiency of the catalytic oxidation unit is achieved and at the same time can be dispensed with an additional heating to heat the exhaust stream. Due to the heat energy released, the exhaust gas flow emerging from the catalytic oxidation unit is also heated. This can be used again completely or in part for drying. In addition, it is possible that only a second portion of the exhaust gas stream (henceforth second exhaust gas stream fraction) is supplied to the catalytic oxidation unit for purification, while a first exhaust gas stream fraction is used again for drying. By reusing the first exhaust gas stream portion for drying, the concentration of the at least one solvent in the exhaust stream may be increased, thereby allowing more efficient operation of the catalytic oxidation unit. It is envisaged that, among other things, a solvent concentration of the exhaust gas flow is detected and monitored by means of sensors. If a predetermined value is exceeded, a quantity of the exhaust gas flow is supplied to the catalytic oxidation unit as the first exhaust gas flow component to a required extent.

In the DE 33 12 704 A1 discloses a drying apparatus for a printing press in which portions of the exhaust gas stream already in use are used to heat the drying gas stream. The mixture of the gas flows is exclusively temperature-controlled. To remove solvents from the exhaust gas stream, a catalytic layer is provided, at which the exhaust gas stream is oxidized. The control of the oxidation process is also based on the temperatures in the exhaust stream.

From the DE 10 2010 026 604 A1 For example, a sheet-fed press and a method for drying printed sheets by means of air flow are known. To optimize the Drying process takes place an admixture of an already heated exhaust gas flow to the still to be heated drying gas flow. The control of the admixture takes place as a function of the temperature and the absolute humidity of the exhaust gas flow. In addition, the controller can also take into account the temperature and the absolute humidity in the drying gas flow. A means for removing solvents from the exhaust stream is also mentioned.

If a plurality of printing units are present in a device, with which the at least one substance mixture is applied to the material web, these printing units can each have drying gas supply lines and exhaust gas discharges, as described in US Pat DE 197 55 812 A1 is described. These can also be controlled individually and as a function of a detected solvent concentration in the exhaust gas flow, whereby an exceeding of a limit value of the solvent concentration can be avoided.

The possibility of increasing the solvent concentration of the exhaust gas stream by repeatedly supplying the first proportion of exhaust gas flow to the drying is for example also from DE 31 20 738 A1 known. In the DE 31 20 738 A1 a method for drying printed or coated webs is described. The running through drying chambers or covered by drying hoods material web is blown with heated air as a drying gas stream and then sucked off again as exhaust gas stream. A first proportion of exhaust gas flow is circulated until a desired solvent concentration is reached and reused for drying. The solvent concentration in the first offgas stream portion is increased to about one half of the lower explosive limit (50% LEL) before being fed as a second offgas stream portion to an afterburner without a catalytic thermal conversion or recovery unit.

A disadvantage of the solutions known from the prior art is that the second proportion of exhaust gas in the range of seconds or less minutes has either periodically or randomly varying solvent concentrations. This also varies the conditions under which one in the catalytic Oxidation unit existing catalyst is operated. For the efficient use of a catalyst, however, constant operating conditions are advantageous.

The invention has for its object to propose a way by which an exhaust gas stream containing at least one solvent can be efficiently cleaned for long periods and in the presence of a catalyst. The object is to be solved for a device for applying mixtures of substances on a material web.

The object is solved by the subject matters of the independent claims. Advantageous embodiments can be found in the dependent claims.

The object is achieved by a device for applying mixtures of substances containing at least one organic solvent to a material web according to claim 1.

The catalytic oxidation unit is a catalyzed thermal oxidation unit.

The core of the invention is the targeted adjustment of a constant concentration of the solvent as working concentration (also referred to as constant working concentration) of the second exhaust gas flow component, whereby this operating parameter of the catalytic oxidation unit is kept stable.

A constant working concentration is to be understood as meaning a constant concentration of the at least one solvent in the second offgas stream component which does not fluctuate by more than 10% of a desired value. It is understood that during the phases of startup and shutdown of the device according to the invention greater fluctuations may occur. If there are several solvents in their respective concentrations in the second exhaust gas stream fraction, the working concentration is understood as meaning a resulting concentration of all the solvents present.

The working concentration is a desired range of concentration values of the at least one solvent in the second exhaust gas stream portion at which the thermal oxidation unit is operated. In the presence of the working concentration, the thermal oxidation unit preferably works completely autothermally or over partial ranges of the working concentration. The working concentration can be freely selected. The selected working concentration is kept constant within the framework of technical fluctuations known to the person skilled in the art. In the course of the procedure, a new working concentration can be selected. For these, the above explained applies accordingly.

A catalytic oxidation unit is understood to mean a device in which, in the presence and with the cooperation of at least one catalyst, the second exhaust gas flow component is thermally converted. Preferably, the working concentration is selected so that a far-reaching or complete thermal reaction of the at least one solvent can be carried out by the catalytic oxidation unit. It is particularly advantageous if the technical design of the catalytic oxidation unit and the operating parameters for their operation, for example, the working concentration, the material and the dimensioning of the catalyst and an inlet temperature of the second exhaust gas flow component, are coordinated so that a thermal conversion is exothermic. During the thermal conversion, it is preferable to release so much energy, in particular heat energy, that the thermal conversion takes place exothermically and the catalytic oxidation unit can be operated autothermally. The catalytic oxidation unit is advantageously an autothermal unit after a start-up phase of the device.

The material of the catalyst is preferably a mixed metal oxide, metal oxide or metal, in particular one or more noble metals. In an advantageous embodiment of the device according to the invention, the catalyst material is a material based on mixed metal oxide, in particular a material of the classes of spinels and perovskites. It is favorable if, as material of the catalyst, one or more materials are selected, through the catalyst volume of which space velocities in a range of preferably 5000 to 20,000 h ^{-1 are} achieved. For example, a catalyst volume with a space velocity of about 8000 h ^-1 or higher is advantageous. The higher the space velocity is chosen, the smaller the catalytic oxidation unit can be designed. At low space velocities, the residence time of the second proportion of exhaust gas in contact with the catalyst is longer than at higher space velocities. Thus, it is possible over the prior art to lower the temperature at which the thermal conversion is carried out by about 20 to 50 K. Noble metal catalysts do not show this effect at temperatures <280 ° C. The space velocity is a size which may vary during operation of the device according to the invention and, for example, depends on the ratio of the volume flow of the second exhaust gas stream proportion and the volume of the catalytic oxidation unit and the catalyst volume.

The mixture of substances may, for example, be a color of a specific hue. In addition to other substances such as carriers, dispersants and organic chemical compounds, at least one organic solvent is a constituent of the substance mixture. The solvent is preferably already volatile at room temperature (high partial pressure), i. it may preferably be removed at room temperature by blowing a suitable drying gas to a considerable extent from the mixture. By using a heated drying gas, the at least one solvent is even easier to remove because the volatility of the solvent increases with heat input. Also, the capacity for containing solvents is increased with a heated drying gas.

As the drying gas, air is preferably used. The air may already contain a proportion of at least one solvent, but should not be saturated with respect to each of the solvents contained. The air is sucked in on the processing heads. Advantageously, an additional fresh air supply, for example, to a recirculation line available. The fresh air supply is preferably connected via a regulator element with the recirculation line.

The recirculation line serves to return the first proportion of exhaust gas flow to the drying gas line.

In order to give the Trocknungsgasstrom a temperature favorable for drying and to adjust the temperature of the drying gas stream, the individual Trocknungsgaszuleitungen and / or this, in a region of a common drying gas line, upstream of a common heat exchanger is arranged. The one or more heat exchangers can / have a heating unit, by means of which the temperature of the drying gas flow is adjustable, in particular can be increased. It is possible that a controllable bypass of individual heat exchangers or groups of heat exchangers is provided, which are fully, partially or not activated by appropriate control of the control elements, so that the entire, a part or no drying gas is passed through the heat exchanger or the.

The at least one solvent is an organic solvent, in particular acetone, methylpropanol, ethylpropanol or ethanol. Further solvents are, for example, methanol, propanol, isopropanol, ethyl acetate or n-hexane, it being possible in principle to use any suitable organic solvent, alone or in admixture. For example, a solvent is suitable if it has no or tolerable adverse effects on the composition and / or on the web. Any mixtures of organic solvents may also be used. Instead of at least one solvent or of a solvent mixture, it is also discussed below in a simplified manner of one or the solvent.

Another important aspect of the invention is that a drop in an oxygen concentration of the second proportion of exhaust gas flow is avoided or at least allowed only to a very small extent. The oxygen concentration is determined by the oxygen atoms present and not only the presence of molecular oxygen O ₂ . Nevertheless, the oxygen concentration is henceforth also referred to simply as O ₂ content.

The O ₂ content is particularly important for the processes in the catalytic oxidation unit of great importance. From the prior art (eg DE 10 2013 223 845 A1 . DE 29 48 603 A1 ) catalysts are known from or with precious metal (s), which are heated by using a gas heater to an intended operating temperature. As a result of the oxidation of the combustion gases of the heating, the O ₂ content, ie the amount of oxygen atoms available for a catalytic reaction, decreases. Nevertheless, in order to be able to carry out an efficient (oxidative) catalysis, activation temperatures of the catalyst material of around 320 to 650 ° C. must be achieved, which requires a high degree of catalyst stability Energy requirement is connected. If the O ₂ content falls below a certain threshold value, activation of the catalyst material is no longer possible even by increasing the temperature. According to the prior art, the inlet temperatures of the second exhaust gas stream fraction fed to the catalytic oxidation unit are, for example, for an oxidative catalytic conversion of ethanol or ethyl acetate at around 280 ° C. By the input temperature is that mean temperature of the second exhaust gas flow component (averaged over the cross-section) denotes, which this has when it enters the catalytic oxidation unit.

In a favorable embodiment of the device according to the invention, a control unit is provided for controlling an inlet temperature of the second exhaust gas flow component as it enters the catalytic oxidation unit. This control unit is advantageously configured so that the input temperature is set to at most 240 ° C during operation of the device according to the invention, whereby less energy is required to operate the device according to the invention.

In order to counteract a lowering of the O ₂ content, the catalytic oxidation unit is preferably heated flamelessly, ie within the catalytic oxidation unit, no form of combustion is carried out to form a flame. The device according to the invention therefore preferably has heating elements, by means of which flameless heating is enabled.

For example, it is possible that the catalytic oxidation unit is heated indirectly by means of a flame by directly heating with the flame a portion of the outer wall of the catalytic oxidation unit or by heating by means of a flame a heating medium whose heat energy is transferred to the catalytic oxidation unit by means of a heat exchanger. in particular to the catalyst material, is transferred.

In alternative or complementary embodiments of the device according to the invention, the heating can also by means of microwave radiation, infrared radiation, Ultrasonic waves, be realized inductively or by the operation of ohmic resistors. For heating the catalytic oxidation unit and / or for operating the device according to the invention and / or components thereof, energy, in particular electrical energy, from regenerative sources, such as solar radiation or wind, water or tidal power, can be used.

Such a flameless heater has the advantage that the O ₂ content is not lowered by the heating process and that a high O ₂ content for the catalytic oxidation is available compared to the prior art. Due to the high O ₂ content, a larger amount of solvent is thermally convertible than in catalytic oxidation units according to the prior art. Also, the conversion rates and the degradation rates are much higher than in the prior art, since the probability that an oxygen molecule / atom encounters a pollutant molecule is much higher.

In order to make use of the advantages outlined above, the device according to the invention has at least one control circuit for detecting current O ₂ contents and for controlling O ₂ contents of the device according to the invention. A control circuit consists at least of a means for detecting current O ₂ contents, a means for regulating a local O ₂ content and a control unit for controlling the means for regulating a local O ₂ content on the basis of the means for detecting current O. ₂ levels provided readings.

Means for detecting current O ₂ contents are preferably oxygen sensors. The O ₂ content is conveniently detected at the entrance of the catalytic oxidation unit. In further embodiments, it can also be detected at further locations, for example in the exhaust gas line, the drying gas supply line and / or at the drying devices.

A means for regulating a local O ₂ content is, for example, a controllable control element such as a flap or a valve, upon actuation of which an oxygen-containing gas can be mixed with the second exhaust gas flow component. The middle for regulating a local O ₂ content may be arranged in front of an inlet of the catalytic oxidation unit in the exhaust pipe. The means may be arranged in other embodiments in other lines of the device according to the invention, for example in an exhaust gas discharge line, the recirculating air line, the drying gas supply line or another suitable line. It is also possible that in a device according to the invention a plurality of means are arranged for regulation, which are also present on the same or on different lines.

The control unit may be the same one used to adjust the input temperature. It can also be designed as part of a control unit of the device according to the invention.

The control unit is configured in a very advantageous embodiment so that a control of the O ₂ content can be done using a mathematical model calculation. Such a model calculation (henceforth also short: model) serves in particular to avoid high values of the working concentration and low values of the O ₂ content. Too high values of the working concentration may cause the temperature in the catalytic oxidation unit to increase too much and damage the catalyst material. Too low O ₂ contents lead to an incomplete thermal reaction of the at least one solvent.

As the starting data for the creation of a model, the individual configuration of the device according to the invention can be used. In this case, device-side individual design features such as the length and routing of lines, individual parameters such as flows of the exhaust gas, the drying gas, the fresh air, the exhaust air and the performance of components of the device such as fans and / or heating elements can enter the model. In addition, environmental parameters such as ambient and operating temperatures, humidity and / or aeration state of the device environment may be considered in the model.

By means of a model which is individually adapted and verified to a specific device, it is possible to set and regulate a constant working concentration and to set and regulate the O ₂ content. In simplified embodiments of the device, the model may be based on assumptions about selected device-side design features and / or environmental parameters.

To control the O ₂ content, in one embodiment of the device at least one of the controller elements can be controlled by the control unit. By a controlled supply of fresh air, the working concentration and the O ₂ content can be regulated.

In a particularly advantageous embodiment, measured curves of the O ₂ contents and measured values, for example the working concentration, device-side design features and / or environment-side parameters are stored as operating data by the control unit. During a control based on the model, the stored operating data can be used to predict future developments of the values of the O ₂ contents and / or the working concentration in a forward-looking manner. This has the advantage that unwanted positive or negative peak values can be completely or largely avoided by being able to counteract in good time.

In a further development, the control unit is configured such that currently recorded measured values and the effects of the adjustments made are stored in a database and evaluated for future control processes.

The data stored in the database can be data series, ie locally and / or temporally successive measured values of a parameter, for. B. a certain temperature and the O ₂ content (at a certain location). The data can also be data records consisting of several data series. Furthermore, the data records can be changed by adding, changing or removing data series.

On the basis of the recordings and evaluation of the effects of control processes, future control processes can be made more effective by suitably adapting the model, and the model can increasingly be adapted individually to the specific device.

By controlling at least one control element by the control unit, a fresh air portion can be mixed with the exhaust gas flow, the exhaust air flow and / or the drying gas flow. The mixing can already take place with the exhaust gas stream shortly after it leaves the catalytic oxidation unit. A rapid mixing of the exhaust gas flow with the fresh air and the consequent cooling of the exhaust gas flow advantageously cause no heat-related damage to fluidically downstream components of the device, the mixture or the material web occur.

Devices for applying mixtures of substances containing at least one organic solvent to a material web are generally printing machines, regardless of their working principle, as well as painting machines or coating machines.

A processing head in the sense of the application is a device for applying the substance mixture to the material web. A processing head is, for example, a print head or printing unit of a printing press. A machining head can also be a spray head, z. B. with a spray nozzle, or a device for rolling up the substance mixture on the web.

Dryer devices are devices by means of which in each case a drying gas can be inflated as a drying gas stream onto a region of the material web. Typically, a dryer is associated with a machining head. By means of the drying devices, the drying gas stream is usually blown onto the material web near the respective processing head. There are also such driers includes, regardless of a processing head are present. A typical example is a so-called bridge dryer, by means of which a final drying of the material web, which is usually not bound to a processing head, takes place. Bridge dryers are often found in front of areas of a production facility where the material web is rolled up after application of the substance mixture. Components of a dryer device are drying gas supply and exhaust gas discharge. The exhaust gas discharges open into a common exhaust pipe. In addition, a dryer device may have at least one fan for generating the dryer gas flow and / or the exhaust gas flow. In other embodiments, fans may also be present for jointly generating the dryer gas flow and / or the exhaust gas flow of several drying devices.

Drying gas flow and exhaust gas flow are as volume unit drying gas or exhaust gas per unit time, z. B. cubic meters per hour, understood.

A sensor unit is suitable for receiving and processing sensor signals. The sensor signals are received, detected and processed by sensors. As a result, a value, for example a concentration of the solvent in the exhaust gas flow, is provided by the sensor unit on the basis of the sensor signal. The sensor unit preferably communicates with the control unit in terms of data, so that the values provided are made available to the control unit.

The sensor unit is associated with at least one sensor which is arranged in an exhaust gas outlet or in the exhaust pipe. The sensor may be a gas sensor or a gas measuring cell.

In advantageous embodiments of the device according to the invention explosion protection sensors are present in each exhaust gas outlet and / or the exhaust pipe, by which a current concentration of the solvent is detected. If these concentrations reach at least one point of the device values which lie outside a permissible range (between the LEL and the LEL), at least one control element is activated by the control unit and preferably the proportion of fresh air in the exhaust stream increased, so that the concentration of the solvent comes back to within the allowable value ranges.

Several exhaust gas discharges can be combined in at least one common exhaust pipe. At least one sensor can then be arranged in the exhaust pipe. It is also possible that a plurality of sensors are present and the values provided are compared with each other and serve as a basis for control commands of the control unit.

The control unit can be designed as a central computer or one or more decentralized computers. The computer or computers have a program that is suitable for controlling the controller elements.

For example, regulator elements can be controllably adjustable flaps, valves or slides. The controller elements can be controlled by the control unit, preferably in dependence on provided values of the sensor unit.

In a preferred embodiment of the device according to the invention, the first portion of the exhaust gas stream is inflatable again via the recirculation line and via at least one drying gas feed line as a drying gas stream onto the applied substance mixture. By such a configuration, a concentration of the exhaust gas stream is made possible by not yet saturated with solvents gas (air) is used as a drying gas. The extent of the permitted concentration depends on the specifications to be complied with to ensure explosion protection (eg permissible concentration in percent of the LEL) as well as the absorption rate and the absorption capacity, thus the ability of the drying gas to dry the applied substance mixture.

The working concentration is preferably below a permissible for the operation of the device concentration.

It is possible that the drying is operated with concentration values above a specified OEG, while the second exhaust gas flow component is set to values below the LEL and the thermal conversion of the second exhaust gas flow component also takes place below the LEL.

At least data at the start time and duration of each of the predetermined processing periods are available to the control unit. By the control unit each dryer device corresponding to their respective processing periods can be controlled, so that only corresponding to the processing periods drying gas is blown and exhaust gas is sucked.

By predetermined processing periods are meant periods of time during which a substance mixture is applied to the material web by a processing head. In this case, usually only a certain substance mixture, for example a specific color or a colorless lacquer, is applied to the material web by a specific processing head. The processing periods are predetermined, for example, when a material web is to be printed with a recurring pattern. The processing heads are controlled in a defined time regime. In accordance with the defined time regime, the respective substance mixtures are applied to the material web by the corresponding processing heads, so that, as a result, the pattern is effected on the material web. Starting from a processing status at a freely selected time t0, therefore, the beginning (starting time) and the end, and thus also the duration of the current and future processing periods, are predetermined for each processing head.

In this sense, processing periods are also considered to be predetermined if they are dynamically generated on the basis of current measurement data.

A corresponding to the predetermined processing periods control of the respective dryer device can also take into account a required start-up and a follow-up phase of the dryer device. Start-up and follow-up phases may be caused, for example, by the fact that a fan only to drive to a predetermined operating speed. In addition, it may be possible that sufficient and stable drying gas flow is not available during a start-up phase.

It is also possible for at least one drying device to be controllable outside its predetermined processing period by the control unit. This is for example advantageous if an exhaust gas concentration is detected which is above the working concentration or the permissible concentration and therefore a reduction of the exhaust gas concentration is required. By controlling a drying device outside its predetermined processing period, fresh air from the environment of the controlled drying device is made available and can be mixed with the exhaust gas stream.

In an advantageous embodiment of the device, the catalytic oxidation unit is assigned at least one heat exchanger, by which a thermal energy released during the thermal conversion can be transferred wholly or proportionately to the drying gas flow and / or to the second exhaust gas flow component. By using a heat exchanger can advantageously be kept high, the oxygen content in the drying gas flow and in the exhaust gas stream, which is very advantageous for a thermal reaction under running oxidation reactions. The heat exchanger is preferably equipped with a controllable heating element. If it is detected via sensors that the temperature of the second exhaust gas flow component is lower than a temperature desired for the efficient operation of the catalytic oxidation unit, the heating element is activated and the second exhaust gas flow component is reheated accordingly. In this case, preferably the volumetric flow of the second exhaust gas flow component, its temperature, the material of the catalyst and the catalyst volume of the catalytic oxidation unit are taken into account in the control of the heating element.

The second exhaust gas stream component is heated after its passage through the catalytic oxidation unit and is fed as clean air to the heat exchanger. After flowing through the heat exchanger, the second exhaust gas flow component (also known as Clean air referred) via an exhaust discharge, for example, via a chimney or a suitable vent, released to the environment.

The second exhaust gas flow component (clean air) can be fed to at least one further heat exchanger after flowing through the heat exchanger. After flowing through this further heat exchanger, the clean air is released via the exhaust gas discharge to the environment.

It is possible in a further advantageous embodiment of the device according to the invention, that the second exhaust gas stream portion is guided before entering the catalytic oxidation unit through one of the aforementioned heat exchanger, while the first exhaust gas stream portion is passed through the further heat exchanger.

It is favorable if the catalytic oxidation unit has a catalyst volume in which it is possible to work with comparatively low space velocities of, for example, about 8000 h ^-1 . If the space velocities are low, the second exhaust gas stream portion remains in contact with the catalyst material for a longer time, and operation of the catalytic oxidation unit can be operated at lower temperatures, preferably autothermally, than at higher space velocities.

The object is further achieved in a method for providing a constant working concentration of at least one organic solvent in a portion of an exhaust gas flow for an integrated catalytic oxidation unit of a device for applying at least one organic solvent-containing mixtures to a material web according to claim 8.

In a preferred embodiment of the method according to the invention, the working concentration is selected in a range> 6 g / m ³ in ethanol as solvent per cubic meter. The working concentration may be selected in other embodiments of the method according to the invention when using other solvents other than> 6 g / m ³ . Preferably, a concentration is then selected as the working concentration at which an energy content is approximately equivalent to an ethanol concentration of 6 g / m ³ .

The individual exhaust gas streams are always larger than the respective drying gas streams, since a vacuum at the exhaust gas outlet is required to suck off the inflated drying gas stream. It can be inflated simultaneously or successively several drying gas streams and exhaust gas streams are sucked.

If several exhaust gas streams are extracted, they are preferably subsequently combined and forwarded together as an exhaust gas stream (common exhaust gas stream). It is therefore at least the inevitable difference between drying gas flow or drying gas streams and (common) exhaust gas stream passed as a second component of the exhaust gas stream to the catalytic oxidation unit.

The model can be created as an individual model for a specific device. For example, a specific device during a trial operation at different metrologically detected operating conditions, such as solvent concentrations, operating temperatures, ambient temperatures, media streams (exhaust gas, drying gas, fresh air), mixtures and / or material webs operated. In this case, various scenarios of the regulation of the working concentration and / or the temperatures and / or the O 2 content can be tested under controlled conditions and the individual reaction of the specific device can be stored in a database assigned to the respective scenarios or the respective operating conditions.

A reaction of the device is to be understood here as the manner in which a specific device responds to control actions carried out under known operating conditions. For example, an inertia can be determined with which the device responds to the control processes that have taken place. An inertia is for example due to the fact that the media such as exhaust gas, drying gas and fresh air are each moved as streams (media streams) through the device. Depending on the specific design of the device and an individual, for example, component-specific and / or production-related flow behavior, a certain period of time elapses until the initiated control processes show the desired effects.

Based on the database, a future regulation can be made more effective by adapting the model to current operating conditions more effectively than is possible with models that are fixed in the factory.

It is also possible that based on the stored data of the database simulated expected responses of the specific device in scenarios, eg. B. are extrapolated that were not explicitly checked during a trial operation. In addition, it is possible to predict the likelihood of certain device responses occurring and to anticipate and initiate regulatory actions.

For such a predictive control, it is possible, for example, using known scenarios and the data of the database to identify striking data sets or distinctive data sets, the occurrence of undesirable values, such as the working concentration, the O ₂ content and / or temperatures, very much likely to become. By a forward-looking control in the sense described above, it is advantageously also possible to avoid short-term excesses of predetermined limit values. In addition, the device can be operated with small fluctuations of relevant parameters, such as working concentration, O ₂ content and / or temperatures.

Striking data series or distinctive data records can be, for example, sequences of time-dependent measured values of an operating parameter or of a plurality of operating parameters.

Fig. 1

ein erstes Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung als Prinzipskizze einer Druckmaschine,

Fig. 2

ein zweites Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung als Prinzipskizze und

Fig. 3

ein drittes Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung als Prinzipskizze.

The invention will be explained in more detail with reference to embodiments and schematic diagrams. Show it:

Fig. 1

A first embodiment of a device according to the invention as a schematic diagram of a printing press,

Fig. 2

A second embodiment of a device according to the invention as a schematic diagram and

Fig. 3

a third embodiment of a device according to the invention as a schematic diagram.

In an in Fig. 1 shown first embodiment of a device according to the invention are as essential elements processing heads 1, drying devices 2, an exhaust pipe 3, a recirculating air line 6, a catalytic Oxidation unit 8, a sensor unit 10, a control unit 12 and a drying gas line 13 are present.

The description of the first embodiment of the device according to the invention is based on the assumption that the device is in a normal operating state (continuous operation, no start-up or shut-down phase).

For clarity, only three processing heads 1 are shown, which are each formed as a printing unit of a printing press. Each processing head 1 applies color of a hue to a material web M guided past the processing heads 1 in the direction of the arrow over predetermined processing periods. The substance mixture S applied by each of the processing heads 1 is symbolized as a sequence of differently shaped surfaces. The respective color is a substance mixture S which, in addition to color pigments, also contains at least one readily volatile organic solvent.

The substance mixture S applied to the material web M is at least dried in the region of the respective processing head 1 by means of a drying device 2, wherein in each case a drying device 2 is assigned to a processing head 1. The drying device 2 has a drying gas supply line 2.1 for supplying air as a drying gas in the form of a drying gas stream 2.3 to the processing head 1 and for inflating the drying gas stream 2.3 on the material web M. If freshly applied substance mixture S is present on material web M, at least part of the solvent contained in substance mixture S is taken up and removed by the drying gas stream 2.3. Furthermore, an exhaust gas outlet 2.2 is provided on the drying device 2, through which the inflated drying gas flow 2.3 can be discharged again as an exhaust gas flow 5 out of the region of the processing head 1. For the sake of simplicity, it is assumed that the drying gas flow 2.3 in a region of the machining head 1 is inflated onto the material web M in order to dry an applied substance mixture S spatially close to the machining head 1. In order to create a negative pressure in the region of the machining head 1 and thereby The exhaust gas flow 5 of a dryer 2 is greater than the drying gas stream 2.3 of the same dryer device 2. The exhaust gas discharges 2.2 open into an exhaust pipe 3. In the exhaust pipe 3, the individual exhaust gas streams 5 of the individual Dryers 2 as a common exhaust stream 5 combined and forwarded. After the processing heads 1, a bridge dryer 15 is arranged, which completely spans the material web M. The bridge dryer 15 is otherwise constructed and connected as the dryer 2.

Each drying gas supply 2.1 is in each case assigned a fan 4 for generating the drying gas stream 2.3 and controlled by the control unit 12.

In a further embodiment of the device according to the invention, a fan 4 can be assigned to all or several drying gas supply lines 2.1. By controllable control valves of controller elements 7, the supply line and the size of the drying gas stream 2.3 and the drying gas streams 2.3 can be controlled.

In further embodiments of the device according to the invention, only one fan 4 may be present, through which the drying gas streams 2.3 are effected in all the drying devices 2. It is possible in further embodiments that fans 4 are exclusively or additionally associated with the exhaust gas outlets 2.2 and / or the exhaust pipe 3.

At one end of the exhaust pipe 3, a control element 7 is provided, through which the exhaust stream 5 into a first exhaust gas flow share 5.1 and a second exhaust gas flow share 5.2 is divided (each symbolized by arrows). The first exhaust gas stream portion 5.1 is passed into a recirculation line 6, which is connected to the drying gas line 13. Through the circulating air line 6, the first exhaust gas stream portion 5.1 of the drying gas line 13 can be fed so that the first exhaust gas stream portion 5.1 the drying equipment 2 again as a drying gas stream 2.3 or as part of which can be fed.

On the circulating air line 6, a fresh air supply 16 is arranged, which is connected via a control element 7 with the circulating air line 6 in connection.

The first exhaust stream component 5.1 contains a certain proportion during ongoing printing operation of the device, i. a certain concentration, at least one solvent. This fraction is detectable by the sensor unit 10 and by sensors 11 which are signal-technically connected to the sensor unit (not all connections shown for reasons of clarity) and can be provided as the value of the concentration of the solvent. Sensors 11 are arranged in the first embodiment shown in the exhaust pipe 3, in the circulating air line 6 and in the drying gas line 13. Each exhaust outlet 2.2 and the exhaust pipe 3 is associated with a sensor 11, by each of which the concentration of the solvent in the exhaust stream 5 is detected (explosion protection sensors).

In other embodiments of the device, a different number and / or a different arrangement of sensors 11 may be present.

Since the exhaust gas stream 5, as explained above, is always greater than the drying gas stream 2.3, there is always a subdivision into a first and second exhaust stream component 5.1 and 5.2, the difference between the exhaust stream 5 and drying gas stream 2.3 or between the common exhaust stream 5 and drying gas flow 2.3 derive as second exhaust gas stream component 5.2. The second exhaust gas flow component 5.2 passes from the dividing acting control element 7 at the end of the exhaust pipe 3 to a fan 4, which is the fluid catalytic upstream of the catalytic oxidation unit 8. Between the upstream fan 4 and the catalytic oxidation unit 8, a designed as a heat sensor sensor 11 for determining the temperature of the second exhaust gas stream part 5.2 is present.

The catalytic oxidation unit 8 is provided with a mixed oxide as a material of a catalyst having a space velocity of 8000 h ^-1 .

In the catalytic oxidation unit 8 takes place in the presence of the catalyst, a thermal reaction of the solvents contained in the second exhaust gas stream 5.2. The thermal reaction is exothermic, i. with release of heat energy. If the concentration of the solvent in the second exhaust gas stream portion 5.2 is high enough, the catalytic oxidation unit 8 is operated autothermally.

The catalytic oxidation unit 8 is followed by a heat exchanger 9, through which the thermally reacted second exhaust gas stream portion 5.2 is passed as clean air. The heat exchanger 9 communicates with the circulating air line 6, so that by the action of the heat exchanger 9, the first exhaust gas flow component 5.1 can be heated in a controlled manner. For this purpose, sensors 11 for detecting the temperature of the first exhaust gas flow component 5.1 or the thermally converted second exhaust gas flow component 5.2 are present in the circulating air line 6 and after the catalytic oxidation unit. In accordance with the detected temperatures, a control element 7 assigned to the heat exchanger 9 can be actuated by the control unit 12, by the action of which a quantity of heat transferred to the first exhaust gas flow component 5.1 is controllably adjustable. The second exhaust gas flow component 5.2 is discharged to the environment after flowing through the heat exchanger 9 via an exhaust gas discharge 17. In this case, filter 17 (not shown) may be associated with the further purification of the second exhaust gas stream part 5.2 in further embodiments of the device of the exhaust gas outlet.

In addition, the heat exchanger 9 is connected to a supply line of the second exhaust gas stream part 5.2 to the catalytic oxidation unit 8, so that the temperature of the second exhaust gas stream part 5.2 can be controlled increased before the second exhaust gas stream portion 5.2 of the catalytic oxidation unit 8 is supplied. The required heat energy for heating the first exhaust gas flow component 5.1 and / or the second exhaust gas flow component 5.2 is obtained from the second exhaust gas flow component 5.2 leaving the catalytic oxidation unit 8 obtained and transmitted by the heat exchanger 9. The heat exchanger 9 has a heating element 14, which is controlled by the control unit 12. The heating element 14 consists of two independently controllable heating units (shown in simplified form), so that both the first exhaust gas flow component 5.1 and the second exhaust gas flow component 5.2 are independently heatable.

After leaving the heat exchanger 9, the second exhaust gas stream component 5.2 is derived. The heated first exhaust gas stream component 5.1 is guided through the circulating air line 6 into the drying gas line 13. From there, the first exhaust gas flow component 5.1 returns to the drying devices 2. Fresh air supply 16 can be used to mix fresh air supply with the first exhaust gas flow component 5.1 if necessary.

By the control unit 12, the drying devices 2, the controller elements 7, the heating elements 14 and the fan 4 can be controlled. For this purpose, the control unit 12 is signal-technically connected to the aforementioned elements (some of these compounds are shown by dashed lines).

The sensor unit 10 receives the signals transmitted by the sensors 11 and uses these to detect the respective values of the temperatures and concentrations. The values are provided to the control unit 12. In addition, the values may be graphed in a further embodiment of the device. Thus, the temperature and / or concentration values may be displayed on a display of a plant controller.

The values detected by the sensors 11 are also provided to a control unit 18. The control unit 18 is designed as a subunit of the control unit 12 and serves to regulate an O ₂ content of the second exhaust gas flow component 5.2. For this purpose, at least one sensor 11 for detecting the O ₂ content is designed and arranged between the upstream fan 4 and the catalytic oxidation unit 8, so that the O ₂ content of the second exhaust gas flow component 5.2 can be measured by this sensor 11.

The control unit 18 is data-technologically connected to a database 19 in which models are stored, by means of which a control of the O ₂ content of the second exhaust gas stream part 5.2 by the control unit 18 takes place.

In Fig. 2 a second embodiment of a device according to the invention is shown. In essence, the elements and their functioning with the in Fig. 1 shown device match. Instead of the fan 4 in the drying gas supply lines 2.1, a fan 4 is present in the drying gas line 13 through which the drying gas streams 2.3 of all the drying devices 2 are effected. In addition, between the dividing control element 7 at the end of the exhaust pipe 3 and the upstream of the catalytic oxidation unit 8 fan 4, a heating element 14 for the controlled heating of the second exhaust gas stream part 5.2 is present. The heating element 14 is actuated by the control device 12 if the temperature of the second exhaust gas flow component 5.2 is too low for efficient operation of the catalytic oxidation unit 8. A heating of the second exhaust gas stream portion 5.2 by means of the heat exchanger 9 is then optional.

In a further embodiment, the heating of the second exhaust gas flow component 5.2 by means of the heating element 14 is optional.

According to the in Fig. 3 shown third embodiment, the heat exchanger 9 is only intended to heat if necessary only the second exhaust gas stream part 5.2. A heating element 14 upstream of the catalytic oxidation unit 8 is not present, but may be present in further embodiments of the device. The recirculation line 6 with the first exhaust gas stream portion 5.1 leads to the dry gas line 13. At the circulating air line 6, a further heat exchanger 9.1 is arranged, which is equipped with a heating element 14. This heating element 14 is connected to the control unit 12 in connection and can be controlled by this. Through the further heat exchanger 9.1, the second exhaust gas stream portion 5.2 is passed as clean air after it has flowed through the heat exchanger 9. Whose heat energy can be transferred wholly or proportionately to the first exhaust gas stream share 5.1.

In addition, a bypass of the further heat exchanger 9.1 is provided, so that the first exhaust gas stream portion 5.1 is then not passed through the other heat exchanger 9.1, when the temperature of the first exhaust gas stream portion 5.1 is above a threshold of 80 ° C here. In other embodiments, other temperature values may be selected as the threshold value.

In further embodiments of the device according to the invention, a bypass (not shown) may also be provided on the heat exchanger 9.

During operation of a device according to the invention Fig. 1 the material web M is guided past the processing heads 1. In order to obtain a desired pattern on the material web M, the respective processing heads 1 are activated at predetermined processing periods and a substance mixture S is applied to the material web M by them. Each processing head 1 is assigned a substance mixture S in the form of a printing ink. Before the start of a processing period, the control unit 12 controls the drying device 2 associated with the processing head 1 and puts it into operation. Since the machining heads 1 are basically of the same design, the following description refers, by way of example only, to a machining head 1. The fan 4 causes a drying gas flow 2.3 in the drying gas supply line 2.1 and blows it onto the material web M. In this case, the drying gas stream 2.3 passes over the substance mixture S applied to the material web M by the processing head 1, as a result of which proportionate volatile solvents escaping from the applied substance mixture S are taken up into the drying gas stream 2.3. A negative pressure is generated by way of the exhaust gas discharge line 2.2 in that the drying gas stream 2.3 containing the solvent is sucked off as the exhaust gas stream 5. The exhaust gas stream 5 passes through the exhaust gas outlet 2.2 in the exhaust pipe 3. There, the concentration of the solvent in the exhaust stream 5 is detected by a sensor 11 as a sensor signal and transmitted to the sensor unit 10. From the sensor signal, a value of the concentration of the solvent is detected and provided to the control unit 12.

If the value provided is below a desired working concentration at which the catalytic oxidation unit 8 is to be operated, then the dividing regulator element 7 is actuated at the end of the exhaust gas line 3 so that the largest part of the exhaust gas stream 5 is conducted into the recirculation air line 6 as first exhaust gas flow component 5.1 , Only the difference between the exhaust gas stream 5 and the drying gas stream 2.3 is fed to the catalytic oxidation unit 8 as the second exhaust gas stream component 5.2.

The first exhaust gas stream portion 5.1 is fed to the heat exchanger 9 where it is heated and then passed into the drying gas line 13. From there, the first exhaust gas flow component 5.1 is supplied again as a drying gas stream 2.3 corresponding to a further processing period of the processing head 1.

The drying gas flow 2.3 already contains solvent, but has not yet reached its absorption capacity. As described above, in turn applied substance mixture S is dried, wherein the concentration of the solvent in the exhaust gas stream 5 further increases.

Once the desired working concentration has been reached, the dividing regulator element 7 is activated such that the second exhaust gas flow component 5.2 is proportionately increased and the first exhaust gas flow component 5.1 is correspondingly reduced proportionally.

If it is determined that the concentration of the solvent has already exceeded the working concentration or threatens to exceed it during further drying, a drying device 2 is actuated by the control unit 12 whose associated processing head 1 does not undergo any processing period at this time. Additional ambient air, which contains no or only minimal amount of solvent, is sucked into the exhaust gas line 3 via this additionally controlled drying device 2 and the concentration of the solvent in the exhaust gas flow 5 is reduced.

Such a reduction of the concentration can be triggered as a precaution, if the detected concentration of the solvent is already so high that further drying, for example by supplying a further exhaust stream 5 from a further dryer device 2, to exceed the desired working concentration or a maximum allowable concentration would lead. Such a future supply of a further exhaust gas stream 5 may be known since the control unit 12, the predetermined processing periods of the individual processing heads 1 are available and thus a predictive control of the concentration ratios in the device is possible. The admixing of ambient air to the exhaust gas stream 5 takes place in such quantities that the second exhaust gas stream component 5.2 has the desired working concentration.

The temperature of the second exhaust gas flow component 5.2 is detected by means of a sensor 11 and compared with a desired temperature. The desired temperature is in a range over which the catalyst of the catalytic oxidation unit 8 operates particularly effectively. If the temperature of the second exhaust gas flow component 5.2 is too low, the control element 7, by which the second exhaust gas flow component 5.2 can be fed to the heat exchanger 9, is controlled by the control unit 12 and the second exhaust gas flow component 5.2 is fed to the heat exchanger 9. In this, the desired temperature of the second exhaust gas flow component 5.2 is set. If the desired temperature of the second exhaust gas flow component 5.2 can not be adjusted by means of the heat exchanger 9 alone, the heating element 14 of the heat exchanger 9 is additionally activated and the second exhaust gas flow component 5.2 is heated accordingly.

In the catalytic oxidation unit 8, the second exhaust gas flow component 5.2 is thermally converted and the heat energy thereby obtained is used to heat the first and second exhaust gas flow components 5.1 and 5.2 by means of the heat exchanger 9.

For controlling the O ₂ content of the second exhaust gas stream part 5.2, a general model for controlling the O ₂ content in the database 19 is stored before the device is put into operation, which is controlled by the control unit 18 is repeatedly retrievable. The device is subjected to different operating conditions during a trial operation. In this case, various parameters, such as the solvent concentration, the speed of the fan 4, the achieved working concentration, the O ₂ content, temperatures, flow velocities and flow rates, recorded and stored in the form of data sets in the database 19.

On the basis of the data sets thus determined, the general model is individually adapted to the specific device and individual models are stored in the database 19. Based on the datasets and individual models, simulations are also performed for scenarios that were not actually tested during trial operation. These simulations are extrapolations of the local / temporal evolution of acquired data series and / or the derivative (here also subsumed under the concept of extrapolation) of fictitious data series and fictitious data sets.

Both the general model and the individual models are designed in such a way that unwanted overshoots and undershoots of limit values of predetermined parameters are canceled out by control commands of the control unit 18.

In further embodiments of the method, the simulations are used to adapt the individual models such that predicted overshoots and undershoots of limit values do not occur at all. For this purpose, collected data series and data records are searched for distinctive data series or striking data records. If such distinctive data series or distinctive data records are found, an individual model is selected which is assigned to these distinctive data series or distinctive data records. If several individual models are associated with the identified distinctive data series or striking data records, the individual model is selected on the basis of the criterion of the greatest correspondence (similarity) of the data with the individual models available for selection.

During the control thus effected, the response of the device is again detected and used as a record for adapting the general model or for adapting the individual model used for the control.

As a result, the control of parameters such as the O ₂ content is not based on the general model and only when an actual overrun or undercut a threshold, but it will be timely and taking into account the individual reaction (eg inertia) of concrete Device on the basis of a selected individual model control commands given by the control unit 18 to the corresponding controller elements 7.

In practical interpretations of the device according to the invention and the method based on ethanol as solvent it has been found that a temperature offset of 20 K is to be expected per gram of ethanol in one cubic meter of air. The LEL of ethanol is 60 g / Nm ³ , so 50% of the LEL corresponds to 30 g / Nm ³ or to an offset of 600 K. In the practical interpretations, the concentration of the solvent was raised to less than half of the LEL (12 g or 20% LEL). The available oxidation energy is sufficient for use in catalysis and drying. The system is designed to be autothermic at 0.5 g / Nm ³ .

LIST OF REFERENCE NUMBERS

1

processing head

2

drying device

2.1

Drying gas supply

2.2

Flue gas discharge

2.3

Drying gas flow

3

exhaust pipe

4

Fan

5

exhaust gas flow

5.1

first proportion of exhaust gas

5.2

second exhaust gas stream share

6

forced air duct

7

regulator element

8th

catalytic oxidation unit

9

heat exchangers

9.1

another heat exchanger

10

sensor unit

11

sensor

12

control unit

13

Drying gas line

14

heating element

15

bridge dryer

16

Fresh air supply

17

flue gas discharge

18

control unit

19

Database

M

web

S

applied substance mixture

Claims (9)

1. Device for applying substance mixtures in each case containing at least one organic solvent to a material web (M), having

   - a number of processing heads (1) for applying in each case one substance mixture over the durations of respectively predetermined processing periods to the material web (M),

   - a number of drying devices (2) for drying the applied substance mixture (S) by blowing a drying gas flow (2.3) onto the applied substance mixture (S) and sucking off the drying gas flow (2.3) loaded with portions of the solvent as an exhaust gas flow (5), wherein a drying device (2) is associated with each processing head (1),

   - a gas pipeline system having in each case a drying gas inlet (2.1) and an exhaust gas outlet (2.2) per drying device (2) and with an exhaust gas pipe (3) connecting the drying devices (2) and having controllable regulating elements (7) to regulate volume flows in the drying gas inlets (2.1), in the exhaust gas outlets (2.2) and in the exhaust gas pipe (3) and for controlled division of the exhaust gas flow (5) into a first exhaust gas flow portion (5.1) and into a second exhaust gas flow portion (5.2),

   - a sensor unit (10) for detecting and providing values of a concentration of the at least one solvent in the exhaust gas flow (5) as solvent concentration and

   - an integrated catalytic oxidation unit (8) for the thermal conversion of the solvent of the second exhaust gas flow portion (5.2),

   - a control unit (12), by which the regulating elements (7) are individually controllable and which is configured such that control of the regulating elements (7) takes place to set a constant concentration of the at least one solvent as working concentration based on a comparison of the values of the solvent concentration with a range of values of a desired working concentration of the second exhaust gas flow portion (5.2),

   characterized in that
   a regulating unit (18) for regulating an oxygen concentration referred to as O₂ content in the second exhaust gas flow portion (5.2) is present and the regulating unit (18) is in data communication with a database (19), wherein the database (19) is configured such that at least one general model for regulating the O₂ content is stored in the database (19) in a manner so as to be repeatedly retrievable, by which model a drop in the O₂ content of the second exhaust gas flow portion (5.2) is avoided or at least allowed only to a very small extent.
2. Device according to claim 1, characterized in that the regulating unit (18) is part of a control circuit also including at least one means for detecting the current O₂ content.
3. Device according to claim 2, characterized in that the means for detecting the current O₂ content is an oxygen sensor which is arranged at an entry of the catalytic oxidation unit (8).
4. Device according to one of the preceding claims, characterized in that, by means of the control unit (12), at least one drying device (2) is additionally controllable outside of its predetermined processing period, when an exhaust gas concentration is detected which is above the working concentration or the permissible concentration, and, by control of the drying device (2), fresh air is provided from the environment of the controlled drying device (2) outside of its predetermined processing period and can be added to the exhaust gas flow (5).
5. Device according to one of the preceding claims, characterized in that the catalytic oxidation unit (8) contains a catalyst material from the class of perovskites for the thermal conversion of the solvent of the second exhaust gas flow portion (5.2).
6. Device according to one of the preceding claims, characterized in that the catalytic oxidation unit (8) is an autothermally operated unit after an initial phase.
7. Device according to one of the preceding claims, characterized in that the catalytic oxidation unit (8) is associated with a heat exchanger (9) through which a heat energy which is released during the thermal conversion is proportionally transferable to the first exhaust gas flow portion (5.1) and to the second exhaust gas flow portion (5.2).
8. Method for providing a constant working concentration of at least one organic solvent in a portion of an exhaust gas flow (5) for an integrated catalytic oxidation unit (8) of a device for applying substance mixtures in each case containing at least one organic solvent to a material web (M) with the steps:

   - blowing a drying gas flow (2.3) onto a substance mixture (S) applied to the material web (M),

   - sucking off the drying gas flow (2.3) loaded with portions of the solvent as an exhaust gas flow (5),

   - detecting a concentration of the at least one solvent in the exhaust gas flow (5) as solvent concentration,

   - comparing values of the solvent concentration as actual values with the value of a desired working concentration as a target value,

   - setting a constant solvent concentration as a working concentration by regulating a portion of the exhaust gas flow (5) in the drying gas flow (2.3),

   - dividing the exhaust gas flow (5) into a first exhaust gas flow portion (5.1) and a second exhaust gas flow portion (5.2) and feeding the second exhaust gas flow portion (5.2) to a catalytic oxidation unit (8) for the thermal conversion of the solvent contained in the second exhaust gas flow portion (5.2) and

   - regulating an oxygen concentration referred to as O₂ content of the second exhaust gas flow portion (5.2) based on a model so that a drop in the O₂ content of the second exhaust gas flow portion (5.2) is avoided or at least allowed only to a very small extent.
9. Method according to claim 8, characterized in that regulation of the oxygen concentration takes place through controlled feeding of fresh air.

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