EP4096807A1

EP4096807A1 - Method for the dry filtration of a gas flow that carries foreign bodies, and filter device for cleaning crude gas that carries foreign bodies

Info

Publication number: EP4096807A1
Application number: EP21701692.2A
Authority: EP
Inventors: Walter Herding; Urs Herding; Sebastian DANDORFER; Stefan Hajek; Dino Bethke; Klaus Rabenstein; Maximilian Rösch; Thomas Sehr
Original assignee: Herding GmbH Filtertechnik
Current assignee: Herding GmbH Filtertechnik
Priority date: 2020-01-28
Filing date: 2021-01-14
Publication date: 2022-12-07
Also published as: CN115243782A; WO2021151680A1; DE102020112856A1; DE102020112861A1; CN115243783A; US20230079987A1; EP4096806A1; WO2021151681A1; US20230330581A1; JP2023512045A; JP2023525427A

Abstract

A dry filtration process for a gas flow (44) that carries foreign bodies, in particular in a filter device for purifying waste gas produced in additive manufacturing techniques, said process comprising: feeding a crude gas flow (44) containing foreign bodies into a crude gas chamber (15) of a filter unit, which has at least one filter surface separating a crude gas side from a clean gas side; feeding an oxidant (112) into a reaction region, which lies downstream of the filter surface on the crude gas side, such that foreign bodies contained in the material cleaned from the filter surface and/or the crude gas flow (44) react with the oxidant (112) in the reaction region to form foreign bodies containing oxides.

Description

Process for dry filtration of a gas stream that carries foreign bodies, and filter device for cleaning of raw gas that carries foreign bodies

The invention relates to a method for dry filtration of a gas stream carrying foreign bodies, as well as a filter device for cleaning raw gas carrying foreign bodies.

WO 2012/032003 A1 shows a method for dry filtration of foreign bodies with leading gases, for example exhaust air from a paint shop, in which the filter _{surfaces are covered with limestone powder (CaC0 3} ) as a filtration aid before loading with raw gas containing foreign bodies. In this way, pores of the filter can be suppressed from being closed by sticky foreign matter. This coating of filter surfaces with limestone powder before they come into contact with foreign bodies is known as pre-coating. Precoating is typically used to clean exhaust air from wet painting systems.

The object of the invention is to avoid or suppress raw gas fires when filtering raw gases containing inflammable foreign bodies by means of a dry filter, in particular at high operating temperatures.

In the method according to the invention for dry filtration of a gas stream carrying foreign bodies, in particular in a filter device for cleaning off exhaust air resulting from additive manufacturing technologies, a crude gas stream containing foreign bodies is fed into a crude gas space of a filter unit which has at least one filter surface separating a crude gas side from a clean gas side. Furthermore, an oxidizing agent is fed to a reaction area which is located on the raw gas side of the filter surface downstream from the filter surface. The supply of oxidizing agent takes place in such a way that foreign bodies contained in the material cleaned from the filter surface and / or in the raw gas stream react in the reaction area with the oxidizing agent to form oxide-containing foreign bodies. The oxidizing agent can be, for example, air or an oxygen-containing gas.

The basic idea of the present invention consists in rendering foreign bodies contained in the raw gas, which are easily combustible, harmless by deliberately bringing about a conversion of these combustible foreign bodies into an oxidized configuration. In the oxidized configuration, these foreign bodies are generally inert and no longer flammable, so that further handling of these oxidized foreign bodies no longer requires any special precautions. However, it must be ensured that the course of the oxidation reaction takes place in a controlled manner and, in particular, that the thermal energy generated during the oxidation does not lead to the formation of flames or fires. This is achieved by suitable supply of oxidizing agent to a predetermined reaction area and / or further measures for removing the thermal energy produced during the reaction from the reaction area.

The reaction area can, for example, be located downstream of the raw gas space in relation to the transport of foreign bodies that have accumulated on the filter surface and have been cleaned from the filter surface. The reaction area is therefore on the raw gas side, but downstream of the filter surface. If the oxidizing agent is first fed to the downstream reaction area but not to the raw gas space or an area upstream of the raw gas space, the raw gas space remains free of oxidizing agent, so that the actual filtration of the raw gas can take place under largely inert conditions. The maintenance of an inert environment in the raw gas space can also be ensured by the fact that the reaction area - at least when oxidizing agent is supplied - is closed off from the raw gas space.

In addition, the reaction area can be flowed through by a heat transfer fluid for the removal of heat generated during the reaction. The heat transfer fluid can be a fluid stream separate from the oxidizing agent, for example an inert gas such as nitrogen, which is introduced into the reaction area and, after flowing through the reaction area, is discharged from the reaction area. Such a heat transfer fluid can be kept in a circulating flow if, after the heat transfer fluid has been transported away from the reaction region, suitable heat exchangers are provided in which the heat transfer fluid can give off its heat. It is also conceivable and quite preferred that the heat transfer fluid also contains the oxidizing agent. For example, air or a gas mixture of an inert gas with a predetermined content of oxygen can flow through the reaction region. The heat transfer fluid flows through the reaction area, ie a certain amount of heat transfer fluid is supplied to the reaction area per unit of time and the same amount of heat transfer fluid is removed from the reaction area. Furthermore, an agglomerate collecting area can be provided, which is designed to receive material that has been cleaned from the filter surface, in the following: material that has been cleaned off. Foreign bodies deposited on the filter surface or agglomerates containing foreign bodies are collected in the agglomerate collecting area after the filter surface has been cleaned and kept there. It can be provided that the agglomerate collecting area has a first closure device, which is controlled in such a way that it blocks the raw gas space from a discharge area downstream of the raw gas space for the removal of material cleaned from the filter surface or a connection between the raw gas space and the discharge area manufactures. The first closure device can, for example, have a first closure member provided in a delimitation of the raw Gaussian space with respect to its surroundings. By activating the first closure device, the amount of material that gets from the raw gas space to the discharge area per unit of time can be controlled in such a way that a predetermined amount of oxidizable material is always present in the reaction area and thus a predetermined amount of oxidizable material per unit Unit of time is transported through the reaction area. As a result, by appropriately controlling the first closure device, it can be ensured that the amount of heat generated during the reaction of the oxidizable material remains within a tolerable range, so that the temperature in the reaction area does not exceed a predetermined threshold value.

In certain embodiments, the reaction area can lie within the discharge area, so that the discharge area contains the reaction area. The reaction area can then in particular lie downstream of the first closure device, so that when the first closure device is closed, the oxidation taking place in the reaction area does not affect the ambient conditions prevailing in the raw gas space.

In particular, it can be provided that the oxidizing agent is fed to the discharge area. This makes it possible for the raw gas space to remain free, in any case largely free, of oxidizing agent, because the oxidizing agent is fed in the flow direction of material cleaned from the filter surface downstream of the raw gas space. In particular, it can be provided that the raw gas space remains closed with respect to the discharge area when oxidizing agent is supplied to the discharge area.

In further refinements, the discharge area can have a second closure device which is arranged downstream of the first closure device in the direction of flow of material cleaned from the filter surface. The reaction area can then lie between the first closure device and the second closure device. In this way, a well-defined position of the reaction region can be Reichs can be achieved. In particular, by activating the first and second closure devices, it can be ensured that the oxidation of combustible foreign bodies taking place in the reaction area does not have any major effects on areas located upstream (such as the raw gas space) or areas located downstream (such as a collecting container for material cleaned from the filter surface ) takes. The second closure device can in particular have a second closure member designed to delimit the reaction area of the discharge arrangement from an agglomerate collecting container located downstream. In particular, the first closure device can be designed in such a way that it has a lock function. If desired, the second locking device can additionally or alternatively also be designed in such a way that it has a sluice function. For this purpose, the first closure device and / or the second closure device can have two closure organs arranged one after the other or one closure organ with a lock function.

In a further embodiment, a conveying element for transporting material that has been cleaned from the filter surface can be provided in the reaction area. Mechanical conveying elements, in particular a screw conveyor, rotary valve or the like, can be used as the conveying element. The conveying element can in particular be designed in such a way that a transport direction of the material stripped from the filter surface can be reversed in order to better mix the cleaned-off material with oxidizing agent and thus safely render the cleaned-off material inert. It is also conceivable to implement a conveying element by gravity, in that there is a gradient in the reaction area through which the cleaned material will fall. A further measure for promoting the transport of cleaned-off material can consist in the fact that the cleaned-off material is acted upon in the reaction area by means of a fluidizing device. These measures can of course also be combined.

The discharge area can comprise an agglomerate collecting container. The agglomerate collecting container can be located directly downstream of the raw gas space, optionally with the interposition of a first closure device. It is also conceivable that a transport path is also interposed between the first closure device and the agglomerate collecting container, which transport path forms the discharge area or a part of the discharge area. Such a transport path can, for example, form or contain the reaction area, as described above. For those embodiments in which the transport path comprises the reaction area wholly or at least in part, the description is used below that the reaction area forms a reaction path. A second closure device can then be provided between the transport path and the agglomerate collecting container be, by means of which the further transport route can be shut off from the agglomerate collecting container.

In further refinements, as an alternative or in addition to the refinements described above, it can be provided that the agglomerate collecting container comprises the reaction area. Then the oxidation of combustible foreign bodies takes place either exclusively in the agglomerate collecting container or both in the agglomerate collecting container and in the further transport route.

To support the course of the oxidation reaction and / or for better removal of the heat of reaction that occurs, at least one organ for moving material cleaned from the filter surface can be provided in the agglomerate collecting container. Such an organ can work mechanically, in particular in the manner of a screw conveyor or a mixer. Such an organ can also work pneumatically, for example in the manner of a fluidizing device. It is also conceivable to provide an arrangement for pivoting, rocking or moving the agglomerate collecting container. Of course, these configurations can also be combined with one another, for example by providing a fluidizing base in the agglomerate collecting container, pivotable mounting of the agglomerate collecting container and / or additional provision of one or more mixer arms.

In addition, the reaction area can be temperature-controlled, both when it is designed as a reaction section and when it is arranged in the agglomerate collecting container. This can be done, for example, by means of the heat transfer fluid already mentioned. Additionally or alternatively, corresponding heating elements and / or cooling elements can be assigned to a wall surrounding the reaction area for this purpose. On the one hand, it can be advantageous if the reaction area can be heated in order to quickly reach or maintain a certain activation temperature for the oxidation. On the other hand, it will often be helpful if the reaction area can be cooled in order to be able to efficiently dissipate the thermal energy generated during the oxidation. It can also be provided that the reaction area has an ignition device in order to start the reaction of foreign bodies with the oxidizing agent.

In further refinements, it can be provided that filtration aid is fed to the raw gas stream, the filter surface and / or the reaction area. The Filtrati onshilfsstoff is designed such that it suppresses a reaction of foreign bodies with Oxidati onsmittel, in particular with oxygen. The filtration aid is therefore also referred to below as an extinguishing agent. In addition, the filtration aid can also be used to control the temperature of the reaction area, in particular to supply or remove heat. The filtration aid can be, for example, an inorganic material, in particular an inorganic material based on silicon dioxide or an inorganic material based on calcium carbonate can be used as the filtration aid.

The filtration aid can in particular serve to ensure that the oxidation taking place in the reaction area does not get out of control.

The addition of a filtration aid pursues a similar goal as is pursued in the conventional precoating process in which limestone powder (CaC0 ₃ ) is added. The precoating process is to be modified in such a way that a substance is added as a filtration aid which is selected with a view to suppressing a reaction of self-igniting foreign bodies with oxidizing agents, in particular with oxygen, during the filtration. This ensures that fires do not arise or that, after ignition, the further spread of flames is effectively hindered. The filtration aid is easy to dose. In particular, the filtration aid is suitable for forming agglomerates containing foreign bodies. The addition of the filtration aid does not interfere with the functioning of the filter in normal operation (ie without fire). This includes, in particular, that the filtration aid after contact with the foreign body contained gas stream forms a well-adhering, but also easily detachable filter cake on filter surfaces by means of compressed gas pulses.

The raw gas is an uncleaned gas that carries foreign bodies and has not yet passed through a filter device. For example, the raw gas can be a gas (aerosol) or smoke that carries metal particles. The term smoke is intended to denote an aerosol of dust particles and / or liquid droplets in extremely finely divided form that is carried in an air or gas flow. In the case of smoke, the particle diameter is usually 800 nm or smaller. In the case of a raw gas carrying combustible foreign bodies, provision can be made for an inert gas to be provided as the carrier gas, i.e. the proportion of oxygen and other components that can act as oxidizing agents in the carrier gas is kept below a predetermined threshold. In such a case, the filtration of the raw gas also takes place under inert conditions, i.e. the proportion of oxygen and other components that can act as oxidizing agents also remains below a predetermined threshold in the raw gas space. Foreign bodies only come into contact with oxidizing agents such as oxygen when material is being discharged from the raw gas space.

An inorganic material is in particular a material which mainly consists of carbon-free compounds, in particular is free of organic chemical compounds of carbon. Certain carbon compounds such as carbon mo Oxide, carbon dioxide, carbon disulfide, carbonic acid, carbonates, carbides, ionic cyanides, cyanates and thiocyanates are also to be considered as inorganic materials. The inorganic materials include, in particular, silicon dioxide.

Based on silicon dioxide (Si0 ₂ ) or on the basis of silicon dioxide means in connection with the present invention that the filtration aid has silicon dioxide or a silicon dioxide compound as the main component. The filtration aid can also contain other materials which are present in lower mass fractions than silicon dioxide.

The raw gas space is part of the filter device into which the raw gas is introduced. Agglomerates containing foreign bodies are formed by the accumulation of foreign bodies on the filtration aid. Such agglomerates can be formed in the raw gas flow or raw gas space, but in particular when foreign bodies from the raw gas flow accumulate on filter surfaces when the raw gas flow passes through the filter surface of the filter unit into a clean gas space.

Adding filtration aid based on Si0 ₂ is particularly helpful when the raw gas to be filtered contains foreign bodies that are self-igniting or combustible. Such foreign bodies or foreign particles tend to ignite spontaneously. This ignition can often take place without additional input of heat energy from the outside. If foreign bodies have a small particle size, the foreign bodies have a relatively large surface area in relation to their volume, as a result of which the foreign bodies can ignite particularly easily. It can be sufficient for the foreign bodies to rub against one another as a result of the movement in the raw gas flow. Often the foreign bodies are also charged electrostatically when they rub against each other, which leads to an additional ignition source due to electrical discharges. The addition according to the invention of filtration aids based on silicon dioxide reliably suppresses such self-ignition in the raw gas.

The foreign bodies can, for example, contain metals or be metals and have a granular, in particular chip-like, powdery or smoky configuration. The foreign bodies can in particular have a configuration that is not completely or even not at all oxidized. In particular, the foreign bodies can be titanium powder or titanium shavings. The foreign bodies can be metallic foreign bodies that are not or not completely oxidized. Such foreign bodies arise, for example, in the additive manufacturing of metallic workpieces, through the use of powdery metallic materials when building up workpieces in layers from a powder bed. Typical metals that are used in such processes and that can lead to combustible foreign bodies in the exhaust air are titanium, aluminum, magnesium and their alloys, as well as many steels such as structural steel, heat-treated steel, high-quality yawed stainless steels. The proposed addition of a filtration aid based on Si0 ₂ in additive manufacturing processes in which titanium and / or aluminum-magnesium alloys are used has proven to be particularly suitable for suppressing raw gas fires. The laser sintering process is known, for example, as an additive manufacturing process that produces exhaust gases that tend to spontaneously ignite.

When added, the filtration aid can have a granular, in particular powdery, configuration. This allows precise metering of the filtration aid into the raw gas stream and / or into the filter device, in particular for covering filter surfaces (precoating). In addition, a corresponding filtration aid enables a simple feed mechanism, such as a flap or a pressurized gas feed, to be used. The finer-grained the filtration aid is when added, the more efficient the formation of ignition-retarding agglomerates.

The filtration aid can be configured in such a way that it binds metal-containing foreign bodies with a granular configuration in agglomerates, in particular at temperatures of 600 ° C. or more, in particular at temperatures of 650 ° C. or more, in particular at temperatures of 700 ° C. or more, in particular at Temperatures of 750 ° C or more, especially at temperatures of 800 ° C or more. Depending on the filtration aid, temperatures of up to 1000 ° C., in particular up to 1250 ° C., in particular up to 1500 ° C., can be reached without excessively inhibiting the formation of agglomerates and / or causing the decomposition or disintegration of agglomerates to an undesirably large extent . The agglomerates formed are not or only with difficulty inflammable in the temperature ranges mentioned, so that a higher level of operational reliability compared to conventional filter devices is possible as a result. Numerous Si0 ₂ glasses begin to soften at temperatures above 600 ° C. and can then form agglomerates with foreign bodies. Depending on the configuration of the Si0 ₂ material, for example by adding additives or forming a glass foam, the temperature at which softening begins can be varied in a suitable manner.

The agglomerates can transition into a flowable configuration, which resembles a glass melt, when heated to a great extent and, after cooling below the glass transition point, transition into a glass-like configuration. The filtration aids melt and thereby enclose the foreign bodies in the melt, so that an inertization already takes place in this state. After the melt has solidified, a glass-like configuration is formed. To form a flowable configuration, it can in particular after heating to temperatures of 600 ° C or more, in particular of 650 ° C or more, in particular of 700 ° C or more, in particular of 750 ° C or more, in particular of 800 ° C or more more to come. The agglomerates can have a glass-like configuration after cooling below the glass transition temperature. In this way, contact of the oxidizing agent with the metal-containing foreign body can be avoided.

The filtration aid can in particular be a material which has a glass-like configuration or which can be converted into a glass-like configuration under the action of heat.

Materials based on silicon dioxide with a vitreous configuration are made from a solid and have an amorphous or at least partially crystalline structure. Such glasses have silicon dioxide as their main component and their network is mainly formed from silicon dioxide. This includes so-called silicate glasses in particular. The silicate base glass can be present in its pure form, for example as silica glass. Quartz glass is also conceivable if higher softening temperatures are desired. In addition to the silicate base glass, additional components can also be present, for example phosphate, borate, and the like.

The filtration aid can have at least one of the following materials as the main component: expanded glass spheres, glass powder, silicon dioxide particles (Si0 ₂ particles), quartz powder or a mixture of at least two of these materials. In particular, well-suited glass materials are those made from recycled waste glass (recycled glass), such as expanded glass or foam glass. Expanded glass is produced by grinding old glass fragments and adding binding and / or expanding agents to them. This results in roughly round grains with small, gas-filled pores. Expanded glass can be produced in grain sizes from 0.04 to 16 mm. The granulate has a closed pore structure. Foam glass, especially foam glass crushed stone, is made in a similar manner. Expanded glass or foam glass can be manufactured in such a way that the lower limit for the temperature at which the softening range begins and / or the glass transition temperature assumes a value between 600 ° C and 750 ° C.

In the event of a fire, the initially formed still powdery or granular agglomerates of filtration aid and metal powder soften or melt under the action of heat. The flowable glass melt surrounds the metal-containing foreign bodies and makes them inert. After the melt has solidified, a glass-like structure is formed, with metal-containing foreign bodies being permanently enclosed in the filtration aid or being enclosed by the filtration aid. As soon as the flowable configuration is created, the individual self-igniting particles of the metal are bound (vitrified) by the filtration aid. A reaction with oxidizing agents, in particular with oxygen (O ₂ ), is difficult or impossible in the vitrified state. A vitrification process of the type described occurs in particular at those points where agglomerates of filtration aids accumulate. In particular, a filter cake that is on the raw gas side on a filter surface and which also wholly or at least largely consists of agglomerates of filtration aids, in the event of heat development (for example in the event of a fire), show such a phase transition from a powdery or granular configuration to a flowable and ultimately glassy configuration. Such a vitrification process can also take place on the surfaces of the cone of material which have formed in an agglomerate collecting area during operation and lead to an efficient inertization of the material stored in the agglomerate collecting area. This vitrification process can be supported by covering the surface of the cone of bulk material forming in the agglomerate collecting area with a layer of filtration aid from time to time.

In the event of a fire, the agglomerates formed can remain chemically stable at temperatures of up to 650 ° C, in particular at temperatures of up to 750 ° C, in particular at temperatures of up to 850 ° C, in the presence of an oxidizing agent (usually oxygen) , in particular at temperatures of up to 1000.degree. C., in particular at temperatures of up to 1250.degree. C., in particular at temperatures of up to 1500.degree.

The agglomerate collection area, in particular the reaction section and / or the agglomerate collection container, can be specifically charged with an oxidizing agent or oxidizing agent can be introduced into the agglomerate collection area, in particular the reaction section and / or the agglomerate collection container. The introduction of oxidizing agent can take place automatically, in particular in accordance with a control system or software. Alternatively or additionally, manual introduction of oxidizing agent can also be provided. Particularly suitable oxidizing agents are gases or gas mixtures with a sufficiently high proportion of oxygen. In the simplest case, the oxidizing agent introduced can be air. The introduction of oxidizing agent into the agglomerate collecting area, in particular into the reaction section and / or into the agglomerate collecting container, causes material stored in the agglomerate collecting area, especially in the reaction section and / or in the agglomerate collecting container can react with the oxidizing agent. This specifically initiates the reaction that actually needs to be suppressed or at least controlled. The heat of reaction generated during the oxidation leads to an increase in temperature of the filtration aid. When the temperature reaches or even exceeds the vitrification temperature of the filtration aid, the filtration aid changes into a flowable glass-like phase and includes the already oxidized and any non-oxidized agglomerates that may still be present. The resulting phase change of the filtration aid causes the material in the agglomerate collecting area to be vitrified, especially in the reaction zone and / or in the agglomerate collecting container, and thus makes this material insensitive to further oxidation processes and thus harmless. After the glazing has taken place, the danger uncontrolled ignition of material stored in the agglomerate collecting area, in particular in the reaction section and / or in the agglomerate collecting container, when removing the agglomerate collecting area, especially the agglomerate collecting container, from the filter device. This measure allows the material stored in the agglomerate collection area to be transferred in a targeted and controllable manner from a reactive configuration to an inert configuration. The amount of filtration aids and / or oxidizing agent added can be used to control how much material stored in the agglomerate collecting area, in particular in the reaction zone and / or in the agglomerate collecting container, is allowed to react with the oxidizing agent. This he increases the safety of personnel when handling the agglomerate collecting area, especially when changing from containers to receiving cleaned material.

The agglomerate collecting area, in particular the reaction section and / or the agglomerate collecting container, can be charged with oxidizing agent in a temporal context with the agglomerate collecting area, in particular the reaction section and / or the agglomerate collecting container, being charged with filtration aid. In particular, the loading of the agglomerate collecting area (24; 92) and / or the discharge area and / or the reaction area with filtration aid can precede the oxidizing agent, or the agglomerate collecting area, in particular the reaction section and / or the agglomerate collecting container, can be provided with the Oxidation agents are applied after filtration aid has been applied to the pouring cone or to the material stored in the agglomerate collecting area, in particular in the agglomerate collecting container. In particular, the agglomerate collecting area, in particular the reaction zone and / or the agglomerate collecting container, can be exposed to the oxidizing agent before an agglomerate collecting area assigned to the agglomerate collecting area is released from its holder and removed. If, after removing the agglomerate collecting container, the material in the agglomerate collecting container comes into contact with atmospheric oxygen, the flammable substances or mixtures are rendered harmless by vitrification or conversion into an inert, oxidized configuration, so that the risk of uncontrolled oxidation or a fire no longer exists.

The agglomerates formed from the filtration aid and foreign bodies have, after the action of heat, a shell enclosing foreign bodies with a vitreous configuration, so that no foreign bodies or foreign bodies come into contact with the oxidizing agent. This reliably prevents a fire in the raw gas space, in a raw gas supply line upstream of the raw gas space of the filter device and / or in an area downstream of the filter device, in particular in an agglomerate collecting area or a line leading to an agglomerate collecting area. A chemically resistant substance can form from the filtration aid, which can hermetically seal the self-igniting foreign bodies before they can ignite. The chemically resistant substance formed from the filtration aid can even become flowable under the action of heat and thus suffocate flames after foreign bodies have ignited. Silicon dioxide glasses in particular remain chemically stable as a melt up to high temperatures and do not decompose under the influence of oxygen or other oxidizing agents. In particular, silicon dioxide glasses do not split off any oxygen-containing functional groups, even at high temperatures.

The filtration aid can be designed in such a way that when heated to temperatures of 600 ° C or more, in particular at temperatures of 650 ° C or more, in particular at temperatures of 700 ° C or more, in particular to temperatures of 750 ° C or more , especially at temperatures of 800 ° C or more, does not split off any elements or compounds that can act as oxidizing agents. In particular, the filtration aid can be designed in such a way that it remains chemically stable up to temperatures of 1000 ° C., in particular up to temperatures of 1250 ° C., in particular up to temperatures of 1500 ° C., and in particular does not split off any elements or compounds that are Oxidizing agents can act.

The filtration aid can have an average particle size of 10 to 30 μm, preferably between 15 and 25 μm. The mean particle size is understood to mean that the majority of the particles of the filtration aid have a diameter that is between 10 and 30 μm. All information relates to the X50 value, i.e. 50% of the particles have diameters in the specified range.

Depending on the raw gas to be filtered, the filtration aid can have a softening point or a glass transition temperature of 600 ° C or more, in particular 650 ° C or more, in particular 700 ° C or more, in particular 750 ° C or more, in particular 800 ° C or more, and up to 1000 ° C, in particular up to 1250 ° C, in particular special up to 1500 ° C. In the event of a fire, this allows a phase change of the filtration aid, i.e. transition of the filtration aid into a flowable state, and thus a vitrification of the foreign bodies. This means that a fire can be reliably avoided or stopped.

The method can furthermore comprise distributing or atomizing the filtration aid in the raw gas space and / or in the reaction area, in particular uniform distribution over components arranged in the raw gas space and / or in the reaction area, such as filter elements and raw gas chamber walls or walls in the discharge area of the filter device; especially in the area of the reaction zone and / or in the agglomerate collecting tank. In the process, agglomerates containing foreign bodies deposited on the filter surface can be cleaned off and collected and stored in an agglomerate collecting area. It can be provided that the agglomerate collecting area is acted upon with filtration aid.

The agglomerate collecting area can be acted upon when the agglomerate collecting area holds a predetermined amount of agglomerates. This prevents the amount of agglomerates lying against one another from exceeding a certain amount in order to reduce the risk of the agglomerates igniting.

Before removing an agglomerate collecting container assigned to the agglomerate collecting area, the agglomerate collecting area can be charged with filtration aid in such a way that the agglomerates containing foreign bodies collected in the agglomerate collecting area or in the agglomerate collecting container are covered with a layer of filtration aid. After the agglomerate collecting area has been charged with filtration aid, the agglomerate collecting area can additionally be charged with an oxidizing agent, in particular after filtration aid has been applied to material stored in the agglomerate collecting area and before the agglomerate collecting container is removed.

The agglomerate collecting container can in particular be a disposable container intended for single use only. After the agglomerate collecting area has been charged with filtration aid and oxidizing agent, the agglomerate collecting container can be removed and disposed of. Since after the addition of Oxidationsmit tel, the cleaned material has already been vitrified in the agglomerate collection container before it was removed from its holder, it is ensured that all material is bound in the agglomerate collection container and that it can be safely disposed of in the usual way .

The method according to the invention and the device according to the invention can be used for cleaning foreign bodies from a gas stream in a filter device, in particular in a device of one of the following types:

Device for the suction of exhaust gases that arise from additive manufacturing of workpieces from powdered metallic starting materials;

Device for the elimination of smoke gases that are generated during the manufacture of workpieces by means of laser-sintering processes;

Device for removing air pollution in a laser beam welding system or other welding fume extraction system, Device for removing impurities in flue gases, especially in flue gases that occur in additive manufacturing or in thermal processes.

A filter device according to the invention for cleaning raw gas carrying foreign bodies comprises at least one filter element with at least one filter surface in a raw gas space, to which a raw gas stream containing foreign bodies can be fed. Furthermore, an oxidizing agent feed device is provided which is designed to feed an oxidizing agent to a reaction region which is located on the raw gas side of the filter surface downstream of the filter surface. The oxidizing agent supply device is designed in such a way that foreign bodies contained in the material cleaned from the filter surface and / or the raw gas stream react in the reaction area with the oxidizing agent to form oxide-containing foreign bodies.

The statements made above with reference to the method according to the invention also apply accordingly to the filter device according to the invention.

In particular, the oxidizing agent can be air or an oxygen-containing gas. In particular, the reaction area can be located downstream of the raw gas space. In particular, the reaction area can be shut off from the raw gas space when the oxidizing agent is supplied. These measures help to ensure that the raw gas space remains largely free of oxidizing agents.

In addition, the filter device can have an arrangement for supplying a heat transfer fluid to the reaction area and removing the heat transfer fluid after flowing through the reaction area. Such an arrangement supports the dissipation of thermal energy that arises during the reaction in the reaction area. The heat transfer fluid can also contain the oxidizing agent, e.g. in the form of air or in the form of a gas mixture of an inert gas with a predetermined content of oxygen. The heat transfer fluid flows through the reaction area, i.e. it is fed to the reaction area and discharged from the reaction area.

Furthermore, the filter device can have an agglomerate collecting area which is designed to receive material that has been cleaned from the filter surface. The filter device has a cleaning arrangement, for example a compressed gas cleaning arrangement, by means of which foreign bodies or agglomerates containing foreign bodies are cleaned off over time. This removed material is collected in the agglomerate collection area and held there.

The agglomerate collecting area can in particular have a first closure device which is controllable in such a way that it opens the crude gas space opposite a discharge area downstream of the crude gas space for the removal of from the filter surface. The cleaned material is blocked or a connection is established between the raw gas space and the discharge area. The first closure device can, for example, have a first closure member provided in a delimitation of the raw Gaussian space with respect to its surroundings

By activating the first closure device, the amount of material that gets from the raw gas space to the discharge area per unit of time can be controlled in such a way that a predetermined amount of oxidizable material is always present in the reaction area. As a result, the amount of heat generated during the reaction of the oxidizable material can be kept within a tolerable range.

In certain configurations, the discharge area can contain the reaction area. The reaction area will then generally be located downstream of the first closure device.

The oxidizing agent feed device can be designed in such a way that it opens into the discharge area.

In this way it can be ensured that the raw gas space remains largely free of oxidizing agent, because the oxidizing agent is fed in the flow direction of material cleaned from the filter surface downstream of the raw gas space. To support this, it can be provided in particular that the raw gas space remains closed with respect to the discharge area when oxidizing agent is fed to the discharge area.

In further refinements, the discharge area can have a second closure device which is arranged downstream of the first closure device in the direction of flow of material cleaned from the filter surface. The reaction area can then lie between the first closure device and the second closure device.

The second closure device can in particular have a second closure member designed to delimit the reaction area of the discharge arrangement from an agglomerate collecting container located downstream

In further refinements, a conveying element for transporting material that has been cleaned from the filter surface can be provided in the reaction area. Such a conveying element can be a mechanically operating conveying element, in particular a screw conveyor or a rotary valve. Alternatively or additionally, a gradient can be provided in the reaction area through which the material cleaned from the filter surface will fall. It is also conceivable to use a fluidizing device as the conveying element. device to be provided in the reaction area. All of these measures can be combined with one another. The conveying element can be designed in such a way that a direction of transport of material cleaned from the filter surface can be reversed

In further refinements, the discharge area can comprise an agglomerate collecting container. In particular, it can be provided that the agglomerate collecting container encompasses the reaction area.

For example, at least one organ for moving material cleaned from the filter surface can be provided in the agglomerate collecting container. Such an organ can be, for example, a mechanically operating organ, in particular a screw conveyor or a mixer. It is also conceivable that such an organ is designed as a fluidizing device or that such an organ comprises a fluidizing device. It is also conceivable to mount the agglomerate collecting container in a moveable manner, for example pivotable, rotatable or rockable. The configurations mentioned can also be combined.

In addition, temperature control devices can be provided in certain configurations, by means of which the reaction area can be temperature controlled, in particular heated and / or cooled. In addition, it can be provided that the reaction area has an ignition device in order to start the reaction of foreign bodies with the oxidizing agent.

In further refinements, a filtration aid feed arrangement can be provided with a filtration aid feed line for supplying filtration aid which opens into the raw gas space and / or into the raw gas stream upstream and / or downstream of the raw gas space. The filtration aid is configured in such a way that it suppresses a reaction of foreign bodies with oxidizing agents, in particular with oxygen. The filtration aid can, for example, be an inorganic material, in particular an inorganic material based on silicon dioxide or calcium carbonate.

The filtration aid can be fed to the raw gas stream upstream of the raw gas space, the raw gas space, the filter surface, the discharge area, in particular the reaction area and / or a collection area for material cleaned from the filter surface (hereinafter also called agglomerate collection area).

The filtration aid inlet arrangement can be designed such that the filtration aid forms a glass-like protective layer on the raw gas space or the reaction area facing filter surfaces and / or on raw gas space walls or reaction area walls under the influence of heat and / or can be distributed in the raw gas flow in such a way that it is upstream and / or downstream in the raw gas flow from the fil- ter surface, especially in the discharge area, or on the filter surface under the influence of heat, form glass-like agglomerates of filtration aid and foreign bodies.

The filter device can also have an agglomerate collection container assigned to the agglomerate collection container, which is arranged on an underside of the filter device, the agglomerate collection container having a filtration aid access opening through which the filtration aid can be fed into the agglomerate collection container. The agglomerate collecting container can form the agglomerate collecting area.

The filter device can have a first line through which oxidizing agent can be supplied from an oxidizing agent storage tank and / or filtration aid from a filtration aid storage tank into the raw gas space and / or into a raw gas line opening into the raw gas space and / or into a reaction area or into a reaction path, and in particular a second line, through which oxidizing agent from the oxidizing agent storage tank and / or filtration aid from the filtration aid storage tank can be delivered into the agglomerate collecting tank. The oxidizing agent can be air or an oxygen-containing gas mixture, the oxidizing agent, when it is fed into the agglomerate collecting container, acts on material located in the agglomerate collecting container with oxidizing agent. If desired, the introduction of oxidizing agent can also take place via a third line different from the second line.

The part of a filter device that connects the raw gas space with the agglomerate collecting container can be referred to as the reaction area or reaction section. This reaction area is designed to enable the material cleaned from a filter surface to react with oxidizing agent in order to allow a controlled and therefore safe reaction to take place here. For this purpose, the reaction area can be designed with an oxidizing agent inlet through which the oxidizing agent can be introduced into the reaction area. The filtration aid or the extinguishing agent can also be introduced into the reaction area via the same inlet or a separate inlet. The reaction area can be designed to be closable, for example by one or more shut-off valves or a shut-off device such as a rotary valve, so that the amount of cleaned material can be appropriately controlled so that the reaction in the reaction area does not exceed a predetermined strength. The reaction area can furthermore have an exhaust gas outlet, through which excess oxidizing agent together with oxidation residues, such as soot and other foreign body particles, can be discharged from the reaction area. The reaction area can also contain a transport element, such as a screw conveyor, a fluidizing floor, or a conveyor belt. The screw conveyor rotates the cleaned material through the reaction area. The fluidizing floor is for example a sheet metal or a grid through which a gaseous conveying medium can be passed, so that the cleaned-off material, which is located on or above the fluidizing floor, is transported to a reaction area outlet. The conveyor belt has the same function, but enables this function in a different way.

The filter device can have a material switch that connects the second line to the first line. This enables the filtration aid to be introduced selectively both into the raw gas space and into the agglomerate collecting container. This increases the safety for operating personnel when operating filter devices according to the invention.

The material switch can be controlled in such a way that a flow of filtration aid can be guided selectively through the first line and / or through the second line. An automatic control device can preferably be used for this purpose. Alternatively, the material switch can also be operated by operating personnel who manually manipulate the material switch and thus introduce the flow of auxiliary filtration into the first line and / or the second line.

The agglomerate collecting container can have an oxidizing agent access opening through which oxidizing agent, in particular air or an oxygen-containing gas mixture, can be introduced into the agglomerate collecting container. By adding oxidizing agent, oxidizable material stored in the agglomerate collecting container can be activated in a targeted manner in order to render the oxidizable material harmless by vitrification with a filtration aid and / or conversion of the oxidizable material into inert oxidized material. This increases the safety of service personnel when replacing the agglomerate collecting container.

The filter device can furthermore have an oxidizing agent line which opens into the oxidizing agent access opening of the agglomerate collecting container. Through the oxidizing agent line, oxidizing agent can be deliberately delivered automatically or manually to the agglomerate collecting container. Automatic is to be understood as the fact that a controller takes over the supply of oxidizing agent. In the case of manual feeding, this is done by the service staff by operating a switch or lever to introduce the oxidizing agent into the agglomerate collecting container. In certain embodiments, the second line can also serve as an oxidizing agent line. For example, the introduction of filtration aid into the agglomerate collecting container can take place at the same time as the material in the agglomerate collecting container is charged with oxidizing agent. It is also possible to introduce the filtration aid into the agglomerate collection container and to apply oxidizing agent to the material located in the agglomerate collection container one after the other, for example by means of additional valves in the second line. tion. For example, the first oxidizing agent could be introduced into the agglomerate collecting container and then the filtration aid.

The filter device can also have a metering device designed to set a predetermined amount of filtration aids. This allows a precise delivery of filtration aids into the filter device and thus an increase in the operational reliability of the filter device.

The aforementioned embodiments and advantages of the method according to the invention also apply to the use according to the invention and the filter device according to the invention.

The invention and special embodiments of the invention are explained in more detail below using exemplary embodiments.

FIG. 1 shows a filter device according to the invention in a side view.

FIG. 2 shows the filter device from FIG. 1 in a side view rotated by 90 degrees compared to the view from FIG.

FIG. 3 shows a detailed illustration of a metering unit for the filter device from FIGS. 1 and 2.

FIG. 4 shows a detailed illustration of one end of the filter device from FIG.

FIG. 5 shows a schematic flow diagram of a method according to the invention.

FIG. 6 shows an agglomerate collecting container which is connected to a filter device outlet via a reaction section. In the reaction section, a screw conveyor for conveying material that has been cleaned from a filter surface is angeord net.

FIG. 7 shows an agglomerate collecting container which is connected to a filter device outlet via a reaction section. Two shut-off organs are arranged in the reaction zone.

FIG. 8 shows an agglomerate collecting container which is connected to a filter device outlet via a reaction section. In the reaction section there is a cellular wheel sluice and, downstream of it, two shut-off devices located one behind the other in the direction of flow. FIG. 9 shows a material which has been cleaned from a filter surface and which is passed through a shut-off device into an agglomerate collecting container and thereby crosses an oxidizing agent flow.

FIG. 10 shows an agglomerate collecting container which is connected to a filter device outlet via a reaction section. The reaction section has a shut-off device. An oxidizing agent access is arranged downstream of the shut-off element and an ignition device is arranged further downstream in the reaction section.

FIG. 11 shows an agglomerate collecting container with a conditioning element (heating and / or cooling element) arranged on its outer wall.

FIG. 12 shows an agglomerate collecting container which has an oxidizing agent connection in a region directed towards the bottom, through which oxidizing agent can be introduced into the agglomerate collecting container below the material that has been cleaned from a filter surface.

FIG. 13 shows an agglomerate collecting container with one or more mixer arms which move a material that has been cleaned from a filter surface in the agglomerate collecting container and thus an advantageous mixing of the material with oxidizing agent takes place.

FIG. 14 shows an agglomerate collecting container which can be rotated on an axis of rotation, in particular rotatable about a horizontal axis of rotation, so that a material cleaned from a filter surface is mixed with oxidizing agent.

FIG. 15 shows a schematic view of a reaction section.

FIG. 16 shows a reaction space for the oxidation of cleaned material.

FIG. 17 shows a further exemplary embodiment of a reaction space.

FIG. 18 shows a funnel-shaped embodiment of a reaction space.

FIG. 19 shows the reaction path shown schematically in FIG. 15 with corresponding elements.

FIG. 20 shows a reaction section with a horizontally aligned mixing and transport device. FIG. 21 shows a cross section through a central part of the reaction path from FIG. 20.

FIGS. 1 and 2 show, in side views rotated by 90 degrees with respect to one another, a filter device 10 for cleaning crude gas carrying foreign bodies according to one embodiment. The filter device 10 comprises a filter unit 12 (not shown in FIG. 1, one of the filter elements 14 of the filter unit 12 is indicated in FIG. 2). The filter unit 12 is attached above a raw gas inflow opening 16 in an upper part of a housing 18, which is partially omitted for the sake of clarity. The filter unit 12 comprises several filter elements 14 designed as rigid body filters or dry filters, which are attached to a common holder and run parallel to one another in the vertical direction, as is schematically indicated in FIG. 2, which shows one of the filter elements 14 in its installed position. Each of the filter elements 14 has at least one filter surface to which the raw gas acts. In FIG. 1, the filter surface acted upon by the raw gas is located on the outside of one of the respective filter elements 14.

In the lower part of the housing 18 shown in FIGS. 1 and 2, which encloses a raw gas space 15, a filtration auxiliary supply opening 20 and a raw gas space opening 22 are formed in addition to the raw gas inflow opening 16. These openings 16, 20, 22 are essentially at the same height in an upper region 18a of the lower housing part 18. Alternatively or additionally, the filtration aid feed opening 20 can be arranged in the raw gas space 15 after or next to the raw gas inflow opening 16 in the direction of flow of the raw gas, see above that the raw gas mixes with the filtration aid before the raw gas reaches the filter elements 14. Due to the flame-suppressing effect of the filtration aid, it can also be referred to as an extinguishing agent. In FIG. 1, such a filtration aid feed opening 20 ′ is shown above the raw gas feed opening 16, that is to say in the direction of the filter unit 12. In a subsequent area 18b below this area 18a, the housing 18 takes the form of a funnel with downwardly tapering side walls. At the bottom, the housing 18 is followed by a collecting area 24 in which foreign body-containing material that was retained by the filter elements is collected before it is passed through a disposal opening 26 and a disposal funnel 28, which is located at the lowest point of the collecting area 24, into a Vacuum conveying device 30 is directed and disposed of, see arrow 32 in FIG. 1.

Since the raw gas carries with it combustible foreign bodies, it can be provided that an inert gas is provided as the carrier gas for the raw gas, ie that the proportion of oxygen and other substances that can act as oxidizing agents is kept below a predetermined threshold in the carrier gas. Therefore, the proportion of oxygen and other substances that can act as oxidizing agents also remains in the raw gas space 15 a predetermined threshold. The filtration of the flammable foreign bodies entrained raw gas thus takes place under inert conditions, ie only when material is discharged from the raw gas space 15, foreign bodies come into contact with Oxidationsmit means such as oxygen.

The disposal funnel 28 can be verschlos sen by a valve 34 at its lowest point, which is only opened briefly when foreign body-containing material is to be discharged from the collecting area 24. In order to ensure disposal of the foreign bodies collected in the collecting area 24, which are usually easily self-igniting without filtration aids, there is an inclined fluidizing floor 36 in the collecting area 24, which is supplied with gas via a connection 38. Connected to the connection 38 is a blower, which is only schematically designated 40, through which the pressurized gas or inert gas is passed into the fluidizing floor 36. The gas flow generated in the blower 40 is set so that, on the one hand, the material collected in the collecting area 24 is loosened to such an extent that it can flow easily and can therefore be easily removed through the disposal opening 26, but on the other hand this material cannot be removed from the collecting area area 24 can get into the housing 18 or into the raw gas space 15.

The raw gas flow, indicated schematically by the arrow 44, which carries foreign bodies with it that are to be separated with the device 10, enters the raw gas space 15 enclosed by the housing 18 via a raw gas supply line 54 through the raw gas inflow opening 16, which is on its top side is limited by the raw gas side of the filter unit 12. After entering the raw gas space 15, the raw gas stream 44 is transported to the filter unit 12. On the side of the housing 18 opposite the raw gas inflow opening 16 there is the filtration aid feed opening 20, through which filtration aids can be passed from a storage container 72 into the raw gas space 15. The filtration aids can be introduced into the raw gas space 15 before it is charged with the raw gas stream 44. The introduced filtration aids are then deposited on, in particular, the filter surfaces of the filter elements 14 and / or on the walls of the raw gas space 15, where they each form a layer of filtration aid (precoat layer). The flow of filtration aids passing through the filtration aid feed opening 20 into the raw gas space 15 is denoted in FIG. 1 by an arrow 45.

Alternatively or additionally, a filtration aid feed opening 52 can be arranged in the raw gas feed line 54. The raw gas supply line 54 is connected to the raw gas inflow opening 16. This enables the filtration aid to be introduced into the raw gas stream 44 before it enters the raw gas space 15 of the filter device 10. This results in an advantageous intermixing of foreign bodies contained in the raw gas stream 44 and the filtration aid in order to prevent the self-ignition increase the threshold of the raw gas. Optionally, a baffle plate or a distributor plate 56 can be arranged in the vicinity of the filtration aid feed opening 52 in such a way that the filtration aid is evenly distributed in the raw gas stream 44. For this purpose, the flow of filtration aid is directed at the distributor plate 56, as a result of which particles of the filtration aid rebound "chaotically" from the distributor plate 56, that is, in non-specified paths, and are distributed in the raw gas flow 44. A corresponding distributor plate can also be arranged in the raw gas space 15 at the filtration aid feed opening 20 or 20 ', which enables an even distribution of the filtration aid, in particular on a filter surface of the filter elements 14. The distributor plate can be arranged on the filtration aid feed opening 20 in such a way that particles of the filtration aid rebounding therefrom are guided in the direction of the filter element 14 and adhere to the filter surface of the filter elements 14.

In a lower region of the funnel-shaped housing region 18b there is a connection 48 which is connected to a ring line 46 running horizontally through the housing 18b. The ring line 46 is located above the collecting area 24 and in particular always above the material collected in the collecting area 24. A further blower 50, which is likewise only indicated schematically in FIG. 2, is connected to the connection 48. The blower 50 can, for example, as otherwise also the blower 40, comprise a side channel blower. In a preferred embodiment, the fan 50 is operated continuously when the filter device 10 is in operation. The connection 48 and the ring line 46 are optional features for the filter device 10. In the event that an inert gas is provided as the carrier gas for the raw gas, an inert gas should also reach the raw gas space 15 via the ring line 46.

The filter unit 12 is assigned a compressed gas cleaning unit, not shown in the figures, which is located on the clean gas side of the filter unit 12 above the filter elements 14. At certain time intervals, the compressed gas cleaning unit acts on a respective filter element 14, so that it experiences a pressure surge from its clean gas side. The pressure surge results in foreign bodies deposited on the filter surface on the raw gas side of the respective filter element 14, such as filtration aids and highly self-igniting foreign bodies, detaching themselves from the filter element 14 and falling down as a result of their gravity.

The filtration aid can in particular be a material which has a glass-like configuration or which can be converted into a glass-like configuration under the action of heat. Materials based on silicon dioxide with a vitreous configuration are made from a solid and have an amorphous or at least partially crystalline structure. Such glasses have silicon dioxide as their main component and their network is mainly formed from silicon dioxide. This includes so-called silicate glasses in particular. The silicate base glass can be present in its pure form, for example as quartz glass or silica glass. In addition to the silicate base glass, additional components can also be present, for example phosphate, borate, and the like.

FIG. 3 shows a metering unit 70 for feeding the filtration aid into the filter device 10 or the raw gas stream 44. The metering unit 70 has a storage container 72 which can be filled with the filtration aid via a filling opening 74. The storage container 72 has an outlet 76 at its lower end, from which the filtration aid can be withdrawn if necessary. The outlet 76 is preferably arranged in such a way that the filtration aid is conveyed to the outlet 76 as far as possible by gravity alone. The storage container 72 is fastened in a holder 78. The holder 78 can be provided with one or more weight sensors 79 with which the filling level of the storage container 72 can be determined. From this filling level, a controller 110 can quickly and precisely determine how much filtration aid has been supplied to the raw gas space 15.

A solids injector 80 is arranged at the outlet 76, which can be controlled in such a way that the filtration aid is transported via a connecting line 82 from the solids injector 80 to a valve 84 and then to one or more of the filtration aid feed openings 20, 20 'and 52 will. The solids injector 80 can be actuated pneumatically so that the filtration aid is transported through the connecting line 82 by means of pressurized gas. In FIG. 3, the connecting line 82 optionally includes a material switch 86 which allows a flow of filtration aid to be introduced into a supply line 88. This feed line 88 is connected to a feed opening 90 in a docking plate 98, as a result of which the filtration aid can be transported into an agglomerate collecting container 92 assigned to the agglomerate collecting area 24. Another valve 94 is arranged in the supply line 88 near the supply opening 90 in order to control a filtration aid supply into the agglomerate collecting container 92.

The valves 84, 94 can preferably be designed as flaps or as disk valves. Alternatively, the agglomerate collecting container 92 itself can have a feed opening (not shown) which is connected to the feed line 88 and the valve 94. Alternatively, the supply line 88 can also be connected directly to the storage container 72 by a further solids injector, not shown. In that case, the filtration aid could be introduced into both the raw gas stream 44 and the agglomerate collecting container 92 at different pressures and at the same time. This allows more efficient control of the filter device and further increases the safety during the operation of the filter device 10.

FIG. 4 shows a further embodiment of the filter device 10 in which, instead of the disposal funnel 28 and the vacuum conveying device 30 connected to it the agglomerate collecting container 92 is arranged on the lower housing part 18b. A discharge flap 96 and the docking plate 98 are arranged between the lower housing part 18b and the agglomerate collecting container 92, through which foreign bodies are discharged from the raw gas space 15 into the agglomerate collecting container 92. The docking plate 98 enables a gas-tight connection of the agglomerate collecting container 92 to the discharge flap 96. The agglomerate collecting container 92 has a filling level sensor 100 with which the filling level of the agglomerate collecting container 92 is checked. For example, the fill level sensor 100 can trigger a signal that indicates that the agglomerate collecting container 92 needs to be emptied, or data from the fill level sensor 100 can be used to control the solids injector 80, the material diverter 86 and the valve 94 via the controller 110 to be controlled so that the filtration aid is introduced into the agglomerate collecting container 92 in order to build up a barrier layer of filtration aid on the particles located in the agglomerate collecting container 92. In this way, a tendency for the particles in the agglomerate collecting container 92 to self-ignite is reduced or completely suppressed. It is also possible to periodically introduce filtration aid into the agglomerate collecting container 92 several times, so that layers of foreign bodies and filtration aid alternate.

Furthermore, an oxidizing agent line 114 opens into an oxidizing agent access opening 118 of the agglomerate collecting container 92. Via the oxidizing agent line 114, the agglomerate collecting container can be supplied with an oxidizing agent, for example air or an oxygen-containing gas, which is indicated schematically in FIG. 4. The oxidizing agent access opening 118 has a valve 116, as a result of which the supply of oxidizing agent 112 into the agglomerate collecting container 92 can be controlled or regulated. The valve 116 can be designed, for example, as a flap or as a disk valve.

In particular, it can be provided that the agglomerate collecting container 92 is acted upon with oxidizing agent 112 in a temporal connection with the introduction of filtration aid into the agglomerate collecting container 92. In particular, provision can be made for the agglomerate collecting container 92 to be charged with oxidizing agent after a filtration aid has previously been introduced into the agglomerate collecting container 92. It can also be provided that the agglomerate collector 92 is charged with oxidizing agent before the agglomerate collector 92 is removed from the docking plate 98, for example to replace a full agglomerate collector 92 with a new agglomerate collector. By charging the agglomerate collecting container 92 with oxidizing agent, an oxidation of material located in the agglomerate collecting container 92 is promoted in a targeted manner. This has the effect that, on the one hand, some of the combustible foreign substances located in the agglomerate collecting container 92 are converted into an inert oxidized form and, on the other hand, through the The heat generated during the oxidation process transforms the filtration aid into a vitreous phase and encloses any material still in the agglomerate collecting container 92 - whether combustible or not - in a vitreous coating. This glazing prevents the flammable foreign bodies still present from further contact with Oxidationsmit tel and thus transfers the material in the agglomerate collecting container 92 into a harmless chemically inert configuration.

Alternatively or additionally, it is also possible to introduce oxidizing agent 112 into the agglomerate collecting container 92 via the supply line 88, for example with the aid of a corresponding branch in the supply line 88 upstream of the agglomerate collecting container 92. Collection container 92 required.

With the supply of oxidizing agent 112, an oxidation of filtered foreign bodies in the agglomerate collecting container 92 can be triggered in a targeted manner. The intensity of this specifically triggered oxidation reaction can be easily controlled via the amount and composition of oxidizing agent 112 added. In addition, the filtration aid, which can be added in large quantities if necessary, absorbs excess heat energy and vitrifies the existing reactive material in the agglomerate collecting container 92. In this way, an effective and easily controllable possibility of converting combustible material into inert and harmless material can be found in the Reach agglomerate collecting container 92. This increases the safety when operating the filter device.

When the filter elements 14 are cleaned, pressurized gas is introduced into the filter elements 14 counter to the direction of flow of the raw gas flow, whereby foreign bodies are blown off the filter element 14 by means of the pressure surge and fall via the lower housing part 18b into the agglomerate collecting container 92. As soon as the filling level sensor 100 indicates that the agglomerate collecting container 92 has reached a predetermined maximum filling level, the discharge flap 96 is closed. Then, manually or by means of the controller 110, the valve 94 is opened, the material switch 86 is actuated and the solids injector 80 is activated, so that the filtration aid from the storage container 72 via the connecting line 82, the material switch 86, the supply line 88, the valve 94 and the Docking plate 98 is transported into the agglomerate collecting container 92. Filtration aids are fed into the agglomerate collecting container 92 until a predetermined amount of filtration aids has been entered into the agglomerate collecting container 92 via a weight decrease in the storage container 72 determined by the weight sensors in the holder 78. The amount preferably corresponds to a barrier layer made of filtration aid with a predetermined thickness, for example an approximately 2 cm high barrier layer made of filtration aid in the agglomerate collecting container 92 closed. An oxidizing agent 112 can then be introduced into the agglomerate collecting container 92 via an oxidizing agent line 114 and an oxidizing agent access opening 118. When combustible foreign bodies react with the oxidizing agent 112, the filtration aid is heated in such a way that it vitrifies the foreign bodies and thus prevents any further reaction of the foreign bodies. The agglomerate collecting container 92 can be removed from the filter device 10 without the foreign bodies in the agglomerate collecting container 92 igniting themselves. The barrier layer made of filtration aid ensures that the foreign bodies in the agglomerate collecting container 92 do not ignite by themselves. This is especially true when the barrier layer has assumed a glass-like configuration, for example after exposure to heat in the event of a fire. The agglomerate collecting container 92 can be lowered by the filter device 10 via a lifting and lowering device 99.

A different order for the supply of filtration aid and oxidizing agent is also possible, namely that first oxidizing agent is introduced into the agglomerate collecting container 92 in order to let the foreign bodies oxidize, and then, when the oxidation reaction has taken place, a barrier layer made of the filtration aid to apply to the oxidized foreign matter.

Provision can also be made for the filtration aid and oxidizing agent to be introduced into the agglomerate collecting container 92 through a common opening. In other words, the supply opening 90 for filtration aid and the oxidizing agent access opening 118 can be combined in a common opening. This results in a smaller number of inlet openings in the agglomerate collecting container 92.

The controller 110 is connected via data lines or control lines in particular to the weight sensors 79, the solids injector 80, the valves 84, 94, the material switch 86, and the discharge flap 96 in order to actuate or manipulate them.

FIG. 5 schematically shows a process sequence for dry filtration of a gas flow or raw gas flow carrying foreign bodies in the filter device 10. The filter device 10 is used in particular for cleaning off waste air resulting from additive manufacturing technologies, the waste air forming the raw gas. In step 102, the raw gas stream 44 is fed to the filter unit 12 arranged in the filter device 10 via the raw gas inflow opening 16 and the raw gas space 15. In this case, the raw gas stream 44 contains self-igniting foreign bodies, such as powdery or chip-like metal dusts, which tend to self-ignite on contact with oxygen or under the action of mechanical energy. In step 104, the raw gas stream 44 and / or the filter element 14 is supplied with the filtration aid via at least one of the filtration aid feed openings 20, 20 'and 52, which is mixed with the foreign matter. bodies mixed in the raw gas stream 44 and thereby reduced the tendency to self-ignition. The softening point of the filtration aid is 500 ° C or more. After the softening point has been exceeded, the filtration aid changes to a glass-like configuration and vitrifies the foreign bodies through the associated phase change from an agglomerate of loosely attached solids to a uniform solid with a vitreous configuration. In other words, the filtration aid encloses the foreign bodies with a layer of glass, so that agglomerates of filtration aid and foreign bodies are formed. A supply of oxidizing agent to the foreign body or to the foreign bodies is thus effectively prevented.

FIG. 6 shows the agglomerate collecting container 92, which is connected to the collecting area 24 of the filter device 10 via a reaction section 120, which in this case forms the reaction area. In the reaction section 120 there is a transport element, in this exemplary embodiment a screw conveyor 122, for conveying / transporting material cleaned from a filter surface (in the following paragraphs simply referred to as cleaned material 139). The reaction section 120 can be assigned one or more shut-off devices 124, 126, 128, which belong to the respective closure or shut-off devices. The first shut-off element 124 and the optional shut-off element 126 are arranged between the collecting area 24 and an inlet of the reaction section 120, the inlet in the material flow direction, i.e. in the transport direction of the cleaned material 139 from the raw gas space of the filter device 10 to the agglomerate collecting container 92, is arranged at the beginning of the reaction section 120. The optional shut-off element 126, which is connected downstream of the first shut-off element 124, enables the reaction path 120 to be securely closed off from the collecting area 24 of the filter device with the function of a sluice, so that gas containing oxidizing agent cannot get into the raw gas space 15. The cleaned-off material 139 falls from the collecting area 24 through the shut-off element 124 into a front (upstream) part 130 of the reaction section 120. From there, the cleaned-off material 139 is conveyed on with the screw conveyor 122. In the exemplary embodiment, the screw conveyor 122 is arranged in such a way that it conveys the cleaned material 139 from the front part 130 obliquely upwards, for example at an angle between 20 and 80 degrees with respect to a horizontal plane. At the upper or "rear" end of the screw conveyor 122 or downstream in the material flow direction, the cleaned material 139 falls into a rear or downstream part 132 of the reaction section 120. This rear part 132 is arranged above the agglomerate collecting container 92. Between the rear part 132 and the agglomerate collecting container 92, shut-off elements 126 and 128 are connected in series in the direction of material flow, one of these shut-off elements being optional.

Optionally, an oxidizing agent inlet 212 can be arranged in the reaction section 120 in the region of the screw conveyor 122. Through this oxidant inlet 212 Oxidizing agent can be introduced into the reaction section 120, ie into the area of the screw conveyor 122, where it is mixed with the cleaned material 139 transported by the screw conveyor 122 and causes an oxidation reaction of the cleaned material 139. As a result, the cleaned-off material 139 is oxidized into an inert material 141. In addition to the oxidizing agent, an inert fluid (eg nitrogen (N2)) can also be introduced via the oxidizing agent inlet 212, which mainly serves to remove heat generated during the reaction. An exhaust gas outlet 218 is arranged at the rear end of the screw conveyor 122, through which excess oxidizing agent is discharged from the reaction section 120 together with heat, oxidation residues such as soot and other substances formed during the oxidation. The introduction of the oxidizing agent into the screw conveyor 122 has the advantage that no fluidization is necessary through a stream of oxidizing agent, because the mixing of the cleaned material 139 with the oxidizing agent is done mechanically by the screw conveyor 122. since only a small part of the cleaned-off material 139 can react with the oxidizing agent. In other words, continuous oxidation can be achieved with this. Furthermore, a filtration aid inlet 214, which can also be referred to as a filtration aid inlet, can be arranged in the reaction section 120 such that the filtration aid or extinguishing agent can be introduced into the reaction section 120 in the area of the conveyor screw 122. In the embodiment shown in Figure 6, the filtration aid inlet 214 is downstream of the oxidizing agent inlet 212. The addition of filtration aid is therefore mainly used as a safety measure to ensure that the strongly exothermic oxidation reaction does not get out of control, as well as to dissipate heat.

The shut-off devices 124, 126, 128 make it possible to control the flow of the cleaned material 139 passing through the respective reaction path and thus to influence the heat generated during the reaction of cleaned material 139 with oxidizing agent 142. In some configurations, the control of the shut-off devices and / or the heat transfer fluid flow can be sufficient to control the temperature that occurs, so that the additional addition of filtration aid can be dispensed with. Another aspect of the shut-off devices, in particular the shut-off devices 124 and optionally 126, is that no oxidizing agent from the reaction path 120 can penetrate into the filter device 10, in particular into the crude gas space 15.

In FIG. 6, the agglomerate collecting container 92 also has a gas inlet 134, which is identified as an air supply, and a gas outlet 136, which is identified as an air discharge. In particular, the gas inlet 134 and the gas outlet 136 are located in a cover 137 arranged on the rear part 132 of the reaction path 120. orderly. The agglomerate collecting container 92 is fastened to the cover 137 in such a way that no fluid or solid can escape at a transition between the agglomerate collecting container 92 and the cover 137. Oxidizing agent is introduced into the agglomerate collecting container 92 through the gas inlet 134, so that the cleaned-off material 139 can react with the oxidizing agent and thus an inert material 141 is produced. This reaction generates heat, which is removed from the agglomerate collecting container 92 with the aid of the oxidizing agent stream from the gas outlet 136. Filtration aid can likewise be introduced into the agglomerate collecting container 92 through the gas inlet 134. This design of the agglomerate collecting container 92 can additionally or alternatively be provided in the design of the reaction section described above.

The shut-off devices 124, 126, 128 make it possible to delimit the reaction section 120 from the collecting area 24 and the agglomerate collecting container 92. In particular, they enable targeted activation to control the amount of oxidizable material in the reaction area per unit of time and thus the heat of reaction generated per unit of time. As soon as the shut-off devices 124, 126, 128 ensure that at least the first closure device and optionally also the second closure device are closed, the oxidizing agent can be introduced into the reaction path 120 through the oxidizing agent inlet 212. The shut-off organs 124, 126, 128 can preferably be designed as a shut-off valve, a flap, a slide, a door, or a pinch valve. A pinch valve has an elastic tube which, in order to reduce a flow through the tube, is compressed or squeezed, whereby a diameter of the elastic tube is reduced. The screw conveyor 122 can be designed, for example, like an Archimedean screw.

It is particularly favorable if the shut-off elements 124, 126 at the upstream end and / or the shut-off elements 128, 126 at the downstream end of the reaction path 120 are designed in such a way that they function as a lock. Then, regardless of the operating state of the first closure device at the upstream end or the operational status of the second closure device at the downstream end, the reaction path 120 can be opposed to the passage of oxidizing agent into the raw gas space 15 or into an agglomerate collecting container 92 arranged downstream. This makes it possible to continuously introduce oxidizing agent into the reaction path 120 without a synchronization with the shut-off element of the first or second closure device being necessary. Such a lock function is particularly advantageous for the first closure device at the upstream end of the reaction path 120, because it can prevent oxidizing agent from getting into the crude gas space 15. The lock function can be implemented, for example, in that the The first closure device and / or the second closure device here has two shut-off elements 124, 126 or 126, 128 arranged one after the other.

FIG. 7 shows a further possible embodiment of the reaction section 120 between the collecting area 24 and the agglomerate collecting container 92. The reaction section 120 is located between the shut-off devices 124 and 128, which delimit the reaction section 120 between a reaction section inlet and a reaction section outlet. The reaction section 120 has a gradient between the first shut-off device 124 at the reaction section inlet and the second shut-off device 128 at the reaction section outlet. In the example shown, the slope is vertical, but it could also be inclined at any angle. Furthermore, the reaction path 120 can have the oxidizing agent inlet 212, the filtration aid inlet 214, and the exhaust gas outlet 218, see also FIG. 6. In the material flow direction of the cleaned material 139, the filtration aid inlet 214 can be arranged downstream of the oxidizing agent inlet 212. Furthermore, the oxidizing agent inlet 212 and the filtration aid inlet 214 are arranged on a first side of the reaction section 120, and the exhaust gas outlet 218 is arranged on a second side of the reaction section, the second side preferably being located opposite the first side. A reverse arrangement is also possible. The shut-off element 124 is followed by the optional shut-off element 126 in the material flow direction, the optional shut-off element 126 being arranged in the material flow direction in front of the oxidizing agent inlet 212, in front of the filtration aid inlet 214 and in front of the exhaust gas outlet.

As also shown in FIG. 6, the agglomerate collecting container 92 is located at the reaction section outlet. The gas inlet 134 forms an oxidizing agent inlet, and the gas outlet 136 forms an oxidizing agent outlet. The gas inlet 134 and the gas outlet 136 are designed as in FIG. 6. The gas inlet 134 and the gas outlet 136 are arranged in the cover 137 in such a way that they are arranged on different sides of a material inlet 138 through which the cleaned material 139 is introduced into the agglomerate collecting container 92. This arrangement of the gas inlet 134 and the gas outlet 136 is particularly advantageous since air or oxidizing agent flows through a material flow of the cleaned-off material 139. This allows the material, which is still reactive at this point in time, to be converted into an inert or inert material 141 with the aid of a controlled oxidation. This inert material is then stored in the agglomerate collecting container 92 and can be safely removed from the agglomerate collecting container 92 by service personnel or disposed of together with the agglomerate collecting container 92 if the agglomerate collecting container 92 is designed as a disposable container. In addition, filtration aid or extinguishing agent can be introduced into the agglomerate collecting container 92 through the gas inlet 134, whereby the inert material 141 is separated from ambient air when the agglomerate collecting container 92 is removed. The reaction path 120 and the agglomerate collecting container 92 each form part of a reaction area. This reaction area can be located both in parts of the reaction path 120 and in parts of the agglomerate collecting container 92 or only in part.

In FIG. 7, the reaction path 120 is oriented in such a way that the cleaned-off material 139 falls into the agglomerate collecting container 92 by means of gravity through a tube that is oriented perpendicular to a cover plane in which the cover 137 is arranged. This tube can also be oriented obliquely to the plane of the cover, as long as the material located in the tube reaches the agglomerate collecting container 92 without getting stuck in the tube, preferably at an angle between 20 to 90 degrees with respect to the plane of the cover.

Figure 8 shows a further embodiment. In FIG. 8, too, the reaction path 120 connects the collecting area 24 to the agglomerate collecting container 92. In this exemplary embodiment, the first closure device has a rotary valve 140 upstream of the reaction path 120 in the direction of material flow. The rotary valve 140 is followed by a shut-off element 124, which is optional in this case. The shut-off element 128 then follows the reaction section 120. As soon as the cleaned-off material 139 has passed the shut-off element 128, it falls into the agglomerate collecting container 92. Unless otherwise stated, are the same elements are provided with the same reference numerals. This means that the cover 137 also has the gas inlet 134 and gas outlet 136.

The rotary valve 140 makes it possible to control the material flow of the cleaned-off material 139 and thus to control and / or influence the amount of heat generated when the cleaned-off material reacts with air or oxidizing agent. The Zel lenradschleuse 140 has an axis of rotation about which a paddle wheel can be rotated, the rotation of the paddle wheel being controllable by the controller 110. In the exemplary embodiment, the axis of rotation is aligned horizontally. However, a different orientation of the axis of rotation is also possible.

The reaction path 120 can also have the oxidizing agent inlet 212, the filtration aid inlet 214, and the exhaust gas outlet 218, see also FIG. 6. In the material flow direction of the cleaned material 139, the filtration aid inlet 214 can be arranged downstream of the oxidizing agent inlet 212. Furthermore, the oxidant inlet 212 and the filtration aid inlet 214 are arranged on a first side of the reaction section 120, and the exhaust gas outlet 218 is arranged on a second side of the reaction section, the second side preferably being opposite the first side. A reverse arrangement is also possible. FIG. 9 shows the rear part 132 of the reaction section 120 with the shut-off element 128 and the agglomerate collecting container 92 located downstream in the direction of material flow. In the process, the falling, cleaned-off material 139 crosses the oxidizing agent flow 142, which flows from the gas inlet 134 to the gas outlet 136. When the oxidizing agent flow 142 falls through, the cleaned-off material 139 reacts with the oxidizing agent and is thereby converted into a reactive and / or inert material 141. The heat generated during the reaction is removed through the gas outlet 136 with the oxidizing agent stream, which generally contains a mixture of oxidizing agent, for example oxygen, and an inert component, for example nitrogen or noble gas. The cleaned and now inert material 141 collects at the bottom of the agglomerate collecting container 92. To further increase safety, the filtration aid can suppress the formation or spread of flames through the gas inlet 134 or through a separate filtration aid inlet (not shown), in the following also as an extinguishing agent designated, are let into the agglomerate collecting container 92. The filtration aid reduces the concentration of any combustible material that may still be present in the inert material 141 and, by means of turbulence, ensures contact of combustible residual material with the oxidizing agent, so that conversion takes place as completely as possible. The filtration aid also assists in absorbing the heat of reaction. The filtration aid can be introduced into the agglomerate collecting container 92 at predetermined intervals so that layers of inert material 141 and filtration aid alternate in the agglomerate collecting container 92. As soon as the agglomerate collecting container 92 is sufficiently filled, the service personnel is informed that the agglomerate collecting container 92 can be removed or emptied. A new agglomerate collection container 92 or the previous agglomerate collection container 92 can then be arranged again on the reaction section 120 and filled with inert material 141.

Figure 10 shows a further embodiment. In this case, the reaction path 120 has an S-shape. The first shut-off element 124 is arranged between the collecting area 24 and the front part 130 of the reaction section 120 in order to control the flow of the material removed. The gas inlet 134, through which the oxidizing agent or air can be introduced into the reaction path 120, is also arranged in the front part 130. In particular, the gas inlet 134 is arranged in such a way that the oxidant flow can be introduced into the reaction path 120 coaxially to a central part 143 of the reaction path 120. The cleaned-off material 139 can thus already react in a first step. In the event that the cleaned-off material 139 only reacts poorly or partially with the oxidizing agent 142, an ignition source 144 is arranged in the middle part 143 of the reaction path 120. This ignition source 144 produces an external energy input into the mixture of cleaned material 139 and oxidizing agent, so that the cleaned material 139 is oxidized and thus converted into inert material 141. Furthermore, in the material flow direction after the ignition source 144, filtration aid or extinguishing agent can be introduced into the flow of inert material 141 via the filtration aid inlet 214. This now inert or inert material 141 falls into the agglomerate collecting container 92. The gas outlet 136 is arranged on the cover 137. The excess oxidizing agent is discharged from the agglomerate collecting container 92 through the gas outlet 136, together with the heat of reaction and oxidation residues that arise during the oxidation of the cleaned-off material.

The reaction path 120 of FIG. 10 has a vertical alignment in the front part 130, then merges into the horizontally aligned middle part 143, in order then to be again aligned vertically in the rear part 132. This means that the cleaned-off material from the collecting area 24 first falls through the shut-off element 124 into the front vertical part 130 of the reaction section 120. This material is then conveyed from the gas inlet 134 through the central, horizontal part 143 of the reaction section 120 by means of the oxidizing agent flow. In the rear vertical part 132 of the reaction section 120, the cleaned-off material then falls by gravity into the agglomerate collecting container 92.

The reaction section 120 can also be referred to as a reaction section. This means that in this area cleaned material reacts in a controlled manner with oxidizing agent, so that uncontrolled ignition of the cleaned material is avoided.

FIG. 11 shows the agglomerate collecting container 92 which is arranged in a conditioning device 147 which can both heat and cool the agglomerate collecting container 92. This device has a temperature control element 148, 150, which can be designed as a heating element and / or as a cooling element. The gas inlet 134 and a gas outlet 136 are arranged on the cover 137 of the agglomerate collecting container 92. A pressure gauge 156 and a solenoid valve 158 are assigned to the gas inlet 134. With the aid of the pressure indicator 156, the service personnel can check whether or not pressurized gas is present at the gas inlet 134. With the aid of the solenoid valve 158, the supply of oxidizing agent to the agglomerate collecting container 92 can be monitored or controlled quickly and easily. A filter element 160 and a second solenoid valve 162 are assigned to the gas outlet 136. The solenoid valve 158 and the solenoid valve 162 can be controlled with the control device 110, not shown in FIG. The supply of oxidizing agent 142 into the agglomerate collecting container 92 can be controlled simply and reliably with the solenoid valves 158 and 162. As soon as the Oxidationsmit tel reacts with the cleaned material 139 in the agglomerate collecting container 92, points the oxidizing agent stream applies foreign matter such as soot or other contaminants and carries them out of the agglomerate collecting container 92. In order to avoid this, the filter element 160 is arranged in the gas outlet 136. In the filter element 160, soot and foreign bodies contained in the oxidizing agent stream are filtered out, so that the oxidizing agent stream can be safely released into the environment after leaving the gas outlet 136.

The conditioning device 147 has a container that has the configuration of the agglomerate collecting container 92. The container also has two or more feet 164 which are attached to an underside of the container.

FIG. 12 shows the agglomerate collecting container 92 with the gas inlet 134, which is arranged on a side wall 168 of the agglomerate collecting container 92, preferably on a lower region 170 of the side wall 168. The lower region 170 is in particular a lower half of the side wall 168 of the agglomerate -Collection container 92 seen from a bottom 172 of the agglomerate collecting container 92. The pressure indicator 156 and the solenoid valve 158 are arranged at the gas inlet 134. However, any other type of valve can also be used. A fluidizing plate 176 is arranged in an interior 174 of the agglomerate collecting container 92, which is formed by the bottom 172 and the side wall 168. The fluidizing plate 176 is positioned such that an intermediate space 178 is formed between the bottom 172 and the fluidizing plate 176. The gas inlet 134 is in fluid communication with the intermediate space 178. The cleaned material 139 remains on the fluidizing plate 176 when it falls into the interior 174, so that the oxidizing agent, which through the gas inlet 134 into the intermediate space 178, through the fluidizing plate 176 and is then passed through the cleaned material 139 to the gas outlet 136, with which the cleaned material 139 can react. The material 141 rendered inert in this way is inert and allows safe handling by service personnel. The gas outlet 136 is arranged in the cover 137 of the agglomerate collecting container 92. The gas outlet 136 comprises a filter 160 and the downstream solenoid valve 162 in the direction of flow, see also FIG. 11 in this regard.

With this exemplary embodiment, good mixing of the oxidizing agent with the cleaned-off material is possible.

Figure 13 shows a further embodiment. In FIG. 13, the agglomerate collecting container 92 is arranged on a rotating device 184. The agglomerate collecting container 92 has an axis of rotation 186 which is aligned parallel to the plane of the cover and about which the agglomerate collecting container 92 can be rotated. The lid 137 of the agglomerate collecting container 92 has the gas inlet 134 and the gas outlet 136, just like the pressure indicator 156, the solenoid valve 158, the filter 160 and the solenoid valve 162, see FIG. 11. Furthermore, the lid 137 has the material inlet 138 on. The second shut-off device with shut-off devices 126, 128 is arranged at an end of the material inlet 138 remote from the cover. The rear part 132 of the reaction section 120 can be closed with the shut-off element 126. The shut-off element 126 and the shut-off element 128 form a lock. In order to be able to rotate the agglomerate collecting container 92 around the axis of rotation 186 with the aid of the rotating device 184, it can be provided that at least one of the shut-off devices 126, 128 is closed and the agglomerate collecting container 92 is decoupled from the reaction path 120 so that the agglomerate -Collection container 92 can be rotated about the axis of rotation 186. If the agglomerate collecting container 92 is only pivoted in the rotating device 184, i.e. no complete rotation about the axis of rotation 186 has to take place, it may be sufficient to connect the transport path to the agglomerate collecting container 92 by a flexible connection, in particular a flexible hose .

The lid 137 has two stirring blades 188 which extend from an underside of the lid 137 to the bottom 172 of the agglomerate collecting container 92, but preferably do not touch the bottom 172 before. The agitator blades 188 are designed to mix the cleaned-off material 139, which has collected in the agglomerate collecting container 92, and thus enable better mixing of the cleaned-off material 139 with the oxidizing agent and / or filtration aid. The filtration aid can in particular be an extinguishing agent and in the following also be referred to as an extinguishing agent. In order to enable the oxidizing agent to be mixed with the cleaned material 139, additionally or alternatively, a motor (not shown) can be arranged in the lid, with which the stirring blades 188 can be moved, and the agglomerate collecting container 92 can be rotated about the axis of rotation 186. The heat of reaction that arises during the reaction of the cleaned-off material with the oxidizing agent is transported away or diverted from the gas outlet 136 with the oxidizing agent flow. In addition, it can also be provided here that filtration aid is supplied.

FIG. 14 shows a further embodiment for mixing cleaned material 139 with oxidizing agent 142. To simplify FIG. 14, no material inlet is shown in cover 137. It goes without saying, however, that this will be provided in reality. In FIG. 14, the agglomerate collecting container 92 is mounted rotatably about the axis of rotation 186 in the rotating device 184. The gas inlet 134 is arranged in the cover 137. Furthermore, the cover 137 has two hollow lances 190 which enable a fluid connection between the interior 174 of the agglomerate collecting container 92 and the surroundings of the agglomerate collecting container 92. The lances 190 extend to the bottom 17 of the agglomerate collecting container 92 without touching the bottom 172. At the end of the lances 190 directed towards the bottom 172, the lances 190 each have an opening 194 through which a mixture 146 of oxidizing agent and oxidizing agent residue can escape. As soon as a predetermined amount of cleaned-off material 139 is stored in the agglomerate collection container 92, the agglomerate collection container 92 is rotated about the axis of rotation 186 by approx. 180 °, so that the cleaned-off material is no longer deposited on the floor 172, but on a fluidizing plate 192 which is arranged in the vicinity of the lid 137 of the agglomerate collecting container 92. The oxidizing agent 142 is then introduced in the form of pressurized gas through the gas inlet 134 into the interior 174 of the agglomerate collecting container 92 through the fluidizing plate 192. As a result, the cleaned-off material reacts and becomes inert or inert. The mixture 146, in particular a mixture of gas and smoke, is discharged from the agglomerate collecting container 92 together with heat via the opening 194. The fluidizing plate 192 is arranged in the agglomerate collecting container 92 in such a way that an intermediate space 196 is formed between the cover 137 and the fluidizing plate 192. The gas inlet 134 is arranged in the cover 137 in such a way that the oxidizing agent 142 is first introduced into the space 196 in order to then pass evenly through the fluidizing plate 192 into the agglomerate collecting container 92 or into the interior 174 of the agglomerate collecting container 92.

FIG. 15 shows a general structure of the reaction area. At the upstream end there is a crude gas chamber 198 of the filter device 10. This is followed in the direction of flow of cleaned material 139 by an optional metering device 200, the first shut-off device with the shut-off device 124 (and optionally the shut-off device 126), the reaction section 120, and the second shut-off device with the shut-off element 128 (and optionally the shut-off element 126). A disposal area 220 adjoins the reaction section 120. For example, the agglomerate collecting container 92 can be provided in the disposal area 220. All parts downstream of the first shut-off device form the discharge area, in particular the reaction section 120 and the agglomerate collecting container 92. The reaction section 120 has the oxidizing agent inlet 212 through which the oxidizing agent 142 can be introduced into the reaction section 120. Furthermore, the filtration aid inlet 214 can be formed in the reaction path 120, through which the extinguishing agent can be introduced into the reaction path. Furthermore, the reaction path 120 can have a heat or ignition source 216 which brings about an input of energy into the reaction path 120 and thus initiates the oxidation of the cleaned-off material 139 with an oxidizing agent. In addition, the reaction path 120 has the exhaust gas outlet 218 through which the mixture of oxidizing agent and oxidation residues leaves the reaction path 120 together with heat. During operation, the cleaned-off material 139 is introduced into the reaction section 120. As soon as the shut-off devices 124 and 128 are closed, the oxidizing agent 142 and optionally the filtration aid or extinguishing agent are introduced into the reaction section 120. The cleaned-off material 139 then oxidizes and becomes the inert or inert material 141. After the reaction has taken place, the shut-off device becomes 128 of the second shut-off device is opened and the inert material 141 is discharged into the disposal area 220.

FIG. 16 shows a further embodiment of the reaction section 120. At a first, upper end of the reaction section 120, a material inlet 240 is formed, through which the cleaned-off material is passed into the reaction section 120. The shut-off element 124 of the first shut-off device is arranged at the material inlet 240. The shut-off element 128 of the second shut-off device is arranged at the lower end of the reaction section 120 and closes a material outlet 242. The inert material is discharged from the reaction section 120 through the material outlet 242. The reaction section 120 has a side wall 230. The side wall 230 encloses the reaction path 120 and thus forms the reaction path 120. The filter aid inlet 214 is formed on the side wall 230 in an upper region of the reaction section 120. The oxidizing agent inlet 212 is arranged below the filtration aid inlet 214 in the material flow direction. The inlets 214 and 212 are arranged in such a way that the filtration aid or the oxidizing agent is introduced into the reaction path 120 at approximately a right angle to the direction of flow of the cleaned material 139. The sequence of oxidizing agent inlet 212 and filtration aid inlet 214 could also be reversed and the injection could also take place at a different angle to the direction of material flow. Furthermore, a fluidizing plate 232 is arranged in the reaction section 120. The fluidizing plate 232 is designed as a perforated plate or as a fine-meshed grid. The fluidizing plate 232 extends from the side wall 230 into the reaction path 120 into it. In particular, the fluidizing plate 232 is arranged in such a way that it is arranged in front of the oxidizing agent inlet 212. The fluidizing plate 232 is arranged in the reaction section 120 in such a way that it is attached between the filtration aid inlet 214 and the oxidizing agent inlet 212. From there, the fluidizing plate 232 extends obliquely downward in the direction of a bottom 234 of the reaction path 120, the bottom 234 being formed below the oxidizing agent inlet 212 in the direction of the material flow. In the present exemplary embodiment, the material outlet 242 is arranged decentrally in the bottom 234, specifically in a region of the reaction path 120 which is opposite the oxidizing agent inlet 212 and the filtration aid inlet 214. A temperature control element 236, preferably a heating element, is integrated in a region of the side wall 230, which is arranged opposite the oxidizing agent inlet 212 and the filtration aid inlet 214, in order to accelerate or even start an oxidation reaction in the reaction path 120. In addition, the ignition source 144 can be arranged in the reaction section 120, in particular next to the temperature control element 236. During operation, the cleaned-off material 139 falls through the shut-off element 124 into the reaction section 120 and impacts the fluidizing plate 232. The oxidizing agent 142, which flows through the oxidizing agent inlet 212, introduced into the reaction path 120 through the fluidizing plate 232 via an intermediate space 238 is, flows through the fluidizing plate 232 and mixes with the cleaned mate rial 139, so that the desired oxidation takes place efficiently. As soon as the cleaned-off material 139 has been oxidized, it falls through the shut-off element 128 at the lower end of the reaction section 120 in the direction of the agglomerate collecting container 92 (not shown).

FIG. 17 shows a further exemplary embodiment of a reaction path 120. Here, too, the material inlet 240 is arranged at the upper end of the reaction path 120 and the material outlet 242 is arranged at the lower end of the reaction path 120. The material inlet 240 and the material outlet 242 are preferably arranged along a common axis. The reaction section is bulged in the radial direction so that the diameter of the material inlet is smaller than the larger diameter of the reaction section 120. The reaction section 120 has a cover 238 arranged at the upper end of the reaction section 120 and that at the lower end of the reaction section 120 arranged bottom 234. In the reaction space 210, the fluidizing plate 232 is arranged, which extends from the ceiling 238 to the floor 234. In this exemplary embodiment, the fluidizing plate 232 thus runs essentially in the direction of the material flow. In the example shown, the fluidizing plate 232 has a cylindrical or frustoconical shape. The intermediate space 237, in which the oxidizing agent 142 can be uniformly distributed, is arranged between the side wall 230 and the fluidizing plate 232. The oxidizing agent inlet 212, through which the oxidizing agent 142 can be introduced into the intermediate space, is arranged on the side wall 230. The oxidizing agent then passes from the intermediate space 237 into the reaction space 210, in which the cleaned-off material is located. As a result of the lateral introduction of the oxidizing agent 142 through the fluidizing plate 232, the cleaned-off material can be mixed uniformly with the oxidizing agent 142, so that a particularly efficient oxidation reaction can take place. The temperature control element 236 can preferably be arranged around the material outlet 242. However, it is also possible to arrange the temperature control element 236 at a different point in the reaction section 120. It fulfills the same function here as in FIG. 16. Furthermore, the ignition source 144 can protrude into the reaction path 120.

In the ceiling 238, the exhaust gas outlet 218 is also arranged, through which the Ge mixture of oxidizing agent and oxidation residues as well as heat from the reaction path 120 can be discharged.

FIG. 18 shows a further exemplary embodiment for the reaction section 120. This reaction section 120 has a funnel-shaped configuration, the reaction section 120 having a larger diameter at the upper end, that is to say the end of the material inlet 240, than at the lower end of the reaction section 120 at the end where the material outlet 242 is located on the reaction path 120. The reaction path includes the ceiling 238 extending radially outward from the material inlet 240. The fluidizing plate extends from a radially outer end of the ceiling 238 te 232 in an oblique direction to the material outlet 242 and thus delimits the reaction path 120. The intermediate space 237, in which the oxidizing agent inlet 212 is arranged, is formed between the fluidizing plate 232 and the side wall 230. This funnel-shaped configuration has the advantage that the cleaned-off material 139 reacts with the oxidizing agent 142, is directed to the material outlet 242 by gravity and can then be discharged from the reaction chamber 210 by opening the shut-off element 128. The temperature control element 236 can be arranged around the material outlet 242. Furthermore, the reaction path 120 can have the ignition source 144, which in particular protrudes into the reaction path 120. The exhaust gas outlet 218 is arranged in the ceiling 238, through which the mixture 146 of residues formed during the oxidation, unreacted oxidizing agent, carrier gas (for example nitrogen (N2)) and optionally extinguishing agent, and heat can be discharged from the reaction path 120.

In Figure 19, the reaction path 120 shown schematically in Figure 15 is shown. The rotary feeder 140 is used as the metering device. A reaction path 120 embodied in accordance with FIG. 18 is then connected to this. In addition, the filter aid inlet 214 is arranged in the ceiling 238, through which, if necessary, extinguishing agent 145 can be introduced into the reaction space 210. In addition, in the material flow direction between the fluidizing plates 232 and the shut-off element 128, an area of the reaction chamber 210 is equipped with the temperature control element 236 in order to introduce activation energy into the reaction chamber 210 so that the oxidation reaction of the cleaned-off material 139 and oxidizing agent 142 can be started reliably. In addition or as an alternative to the temperature control element 236, the ignition source 144 can be arranged in the reaction path 120. In the material flow direction, the shut-off member 128 is followed by an agglomerate collecting container 92, so that the cleaned and inert material 141 can be collected in the agglomerate collecting container 92. The agglomerate collecting container 92 can be a disposable or single-use bucket that can be disposed of by service personnel as soon as it is full without explicitly emptying it.

FIG. 20 shows a further exemplary embodiment with the reaction path 120 to which a transport element is assigned. The reaction section 120 runs between an upstream inlet area, which connects to the shut-off devices 124, 126, and a downstream outlet area, to which the shut-off device 128 connects. In the middle part 143 of the reaction section 120 is the transporter, in this embodiment the screw conveyor 122, for conveying / transporting and mixing cleaned material 139. The first shut-off element 124 and the second shut-off element 126 are one behind the other in the direction of material flow between the catchment area 24 and the central part 143 of the reaction line 120 is arranged. The cleaned-off material 139 falls out of the collecting area 24 through the shut-off elements 124 and 126 into the middle part 143. In this embodiment, the screw conveyor is aligned horizontally in order to convey the cleaned-off material 139 in the horizontal direction from the inlet of the reaction section 120 to the outlet of the reaction section 120. At the rear end of the screw conveyor 122 in the material flow direction, an opening is formed on the bottom of a transport path 123 formed along the screw conveyor 122, through which the material transported by the screw conveyor 122 falls through and reaches the shut-off member 128 arranged below. The shut-off element 128 is arranged above the agglomerate collecting container 92 (not shown in FIG. 20). The shut-off element 128 arranged between the rear part 132 and the agglomerate collecting container 92 separates the reaction path 120 from the agglomerate collecting container 92.

In the upstream part of the reaction path 120, e.g. B. in a front half of the middle part 143 of the reaction path 120, the oxidizing agent inlet 212 is arranged. The oxidizing agent 143 can be introduced through this oxidizing agent inlet 212 into the transport path 123 of the screw conveyor 122, where it is mixed with the cleaned material 139 that is transported by the screw conveyor 122 and causes an oxidation reaction of the cleaned material 139. As a result, the cleaned-off material 139 is converted into an inert material 141. The introduction of the oxidizing agent 143 into the transport path 123 has the advantage that no fluidization is necessary through an oxidizing agent flow, because the mixing of the cleaned material 139 with the oxidizing agent 143 is done mechanically by the screw conveyor 122 The filtration aid inlet 214 or extinguishing agent inlet, through which the filtration aid or extinguishing agent can be introduced into the reaction path 120, in particular into the transport path 123, is arranged in a rear half of the middle part 143. In addition, the ignition source 144 can also be arranged here.

At the rear end of the screw conveyor 122, in the present exemplary embodiment opposite the opening formed on the bottom of the transport path 123, an exhaust gas outlet region 258 is arranged. The exhaust gas outlet region 258 has a filter unit 260 which is mounted on a partition wall 262. The filter unit 260 can have one or more filter elements. The partition wall 262 separates the exhaust gas outlet area 258 into a raw gas space 259 and a clean gas space 261. A mixture 146, which is formed from residues formed during the oxidation taking place in the reaction path 120, as well as excess portions of the oxygenate flow, arrives in the raw gas space 259 and optionally the filtration aid stream. The filter unit 260 is designed to filter the mixture 146 and thus to free it from particulate oxidation residues. In the clean gas space 261 there is then a filtered gaseous mixture, which is delivered via the exhaust gas outlet 218, which is connected to the clean gas space 261. is arranged, discharged and, for example, can be released into the environment. In the clean gas space 261, a compressed gas cleaning unit assigned to the filter unit 260 is also arranged, which is designed to generate a compressed gas pulse that acts on the filter element or elements for cleaning. The pressurized gas pulses pass through a pressurized gas opening 263 from a pressurized gas reservoir 264 into the clean gas space and from there to the filter element or elements. The pressurized gas reservoir 264 can preferably be filled with pressurized gas via a pressurized gas line 266. The compressed gas is used to clean the filter unit 260 as soon as the filter performance of the filter unit 260 deteriorates. In this case, the pressurized gas is introduced into the clean gas space 261, as a result of which foreign bodies that have deposited on the filter unit 260 on the raw gas side are cleaned off by the filter unit 260. These foreign bodies then fall from the exhaust gas outlet area 258, through the opening in the transport path 123, through the rear part 132 of the reaction path 120 and, after opening the shut-off element 128 through the shut-off element 128, into the agglomerate collecting container 92 (not shown). This is particularly advantageous because Both the inert material 141 and the foreign bodies that have been cleaned off can be caught in the agglomerate collecting container 92 and can then be ent provided. The temperature element 236 can be arranged at the rear part 132 of the reaction section. For the function of the temperature control element, see Figure 16.

The transport element can also be designed as a paddle mixer instead of a screw conveyor. A paddle mixer has an axis from which a plurality of paddles extend radially away, the paddles being distributed, preferably evenly distributed, in the axial direction on the axis. These paddles can both move the cleaned-off material through the transport path 123 and also enable the cleaned-off material to be advantageously mixed with the oxidizing agent. In this way it can be ensured that preferably all of the cleaned-off material is oxidized, thus preventing subsequent oxidation.

FIG. 21 shows a sectional view 21-21 through the transport path 123 of FIG. 20. The transport path 123 in particular has a trough-like shape. This means that a part 270 directed towards a base has a round cross section and an upper part 272 directed away from the base has an angular cross section. The transport organ, for example the screw conveyor 122 or the paddle mixer, is arranged in such a way that it touches the lower part 270 or moves along the lower part 270 at a distance of a few millimeters, preferably 5 mm.

The transport element can rotate in different directions. For example, the transport element can rotate in such a way that it transports the cleaned-off material 139 to the rear part 132 of the reaction section 120 so that it can be discharged from there into the agglomerate collecting container 92 (not shown). The transport element can also be rotated in alternating directions to ensure thorough mixing of the cleaned th material 139 with the oxidizing agent 142 or the extinguishing agent. In this way, it can alternatively be ensured that the completely cleaned-off material 139 is oxidized with the oxidizing agent 142. It should be expressly pointed out that the variants described above with reference to the individual figures can be combined with one another and are not limited to the figure in which the corresponding variant is described. For a better overview, the same reference numerals have been used for the same components in each of the figures. It goes without saying that the description belonging to a reference symbol also relates to all other figures in which the reference symbol occurs.

The discharge arrangement, in particular the reaction section 120, can be operated continuously, in particular when using shut-off devices with a lock function. The provision of suitable transport devices in the reaction section also favors continuous operation for the oxidation of foreign bodies, in particular the provision of a screw conveyor, a conveying fluid and / or a rotary valve in the reaction section. Batch or intermittent operation is possible, especially when using valves as shut-off devices.

Claims

Expectations

1. A method for dry filtration of a gas stream (44) that carries foreign bodies with it, in particular in a filter device for cleaning off exhaust gas resulting from additive manufacturing technologies, comprising:

Directing a raw gas flow (44) containing foreign bodies into a raw gas space (15) of a filter unit (12) which has at least one filter surface separating a raw gas side from a clean gas side,

Supplying oxidizing agent (112) to a reaction area which is on the raw gas side of the filter surface downstream of the filter surface; in such a way that foreign bodies contained in the material cleaned from the filter surface and / or the raw gas stream (44) react in the reaction area with the oxidizing agent (112) to form oxide-containing foreign bodies.

2. The method of claim 1, wherein the oxidizing agent is air or an oxygen-containing gas; and / or wherein the reaction area is located downstream of the raw gas space (44).

3. The method according to claim 1 or 2, wherein the reaction area is traversed by a heat meransferungsfluid for the removal of heat generated during the reaction.

4. The method according to any one of claims 1 to 3, wherein an agglomerate collecting area (24; 92) is provided which is designed to receive material cleaned from the filter surface, with foreign bodies or agglomerates containing foreign bodies being cleaned up on the filter surface and in the agglomerate collecting area (24; 92) are collected and held.

5. The method according to claim 4, wherein the agglomerate collecting area (24; 92) has a first closure device (96) which is controlled in such a way that it opens the raw gas space (44) opposite a discharge area downstream of the raw gas space for removal from the filter surface Shuts off cleaned material or establishes a connection between the raw gas space (44) and the discharge area, in particular the discharge area contains the reaction area; and the oxidizing agent (112) is fed to the discharge area.

6. The method according to any one of claims 4 or 5, wherein the discharge area has a second closure device, which in the transport direction of the filter surface The cleaned material is arranged downstream of the first closure device (96).

7. The method of claim 6, wherein the reaction region lies between the first closure device (96) and the second closure device.

8. The method according to any one of claims 1 to 7, wherein a För derorgan for transporting material cleaned from the filter surface is provided in the reaction area, in particular a screw conveyor, a rotary valve, a slope and / or a fluidizing device; wherein the conveying element is designed in particular so that a direction of transport of material cleaned from the filter surface can be reversed.

9. The method according to any one of claims 3 to 8, wherein the discharge area comprises an agglomerate collecting container (92),

10. The method of claim 9, wherein the agglomerate collection vessel (92) comprises the reaction region; and / or wherein at least one element is provided for moving material removed from the filter surface in the agglomerate collecting container (92), in particular a screw conveyor, a fluidizing device, a pivoting device for the agglomerate collecting container (92) and / or a mixer.

11. The method according to any one of claims 1 to 10, wherein the reaction area is tem perable, in particular heated and / or cooled, and / or wherein the reaction area has an ignition device to start the reaction of foreign bodies with the oxidizing agent; and / or wherein the foreign bodies are self-igniting; and / or wherein the foreign bodies contain metals or are metals and have a granular, in particular chip-like or powdery, configuration, in particular titanium, aluminum, magnesium, alloys of these elements, structural steel, heat-treated steel, and / or high-alloy stainless steel.

12. The method according to any one of claims 1 to 11, further comprising supplying filtration aid to the raw gas stream (44), the filter surface and / or the reaction area; wherein the filtration aid is configured in such a way that it suppresses a reaction of foreign bodies with oxidizing agents, in particular with oxygen.

13. The method according to claim 12, wherein the filtration aid is an inorganic material, in particular an inorganic material based on silicon dioxide or an inorganic material based on calcium carbonate; and or wherein the filtration aid has a granular, in particular powdery, configuration when added; and / or wherein the filtration aid is configured in such a way that it binds metal-containing foreign bodies with a granular configuration in agglomerates, in particular at temperatures of 600 ° C. or more, in particular at temperatures of 650 ° C. or more, in particular at temperatures of 700 ° C. or more , in particular at temperatures of 750 ° C or more, in particular at temperatures of 800 ° C or more, in particular at temperatures up to 1000 ° C, in particular at temperatures up to 1250 ° C, in particular at temperatures up to 1500 ° C.

14. The method according to any one of claims 12 or 13, wherein the filtration aid has an average particle size of 10 to 30 μm, preferably between 15 and 25 μm; and / or wherein the filtration aid has a softening point of 600 ° C or more, in particular of 650 ° C or more, in particular of 700 ° C or more, in particular of 750 ° C or more, in particular of 800 ° C or more, and up at 1000 ° C, in particular up to 1250 ° C, in particular up to 1500 ° C; and / or wherein the filtration aid has one of the following materials as the main component: expanded glass spheres, glass powder, silicon dioxide particles, quartz powder or a mixture of at least two of these materials.

15. The method according to any one of claims 12 to 14, in which agglomerates accumulated on the filter surface containing foreign bodies are cleaned off and collected and held in an agglomerate collecting area (24), the agglomerate collecting area (24; 92) and / or the discharge area and / or the reaction area is acted upon with filtration aid and / or with oxidizing agent.

16. The method according to claim 15, wherein the loading of the agglomerate collecting area (24; 92) and / or the discharge area and / or the reaction area with filtration aid and / or oxidizing agent takes place if there are in the agglomerate collecting area (24; 92) and / or a predetermined amount of agglomerates is located in the discharge area and / or in the reaction area.

17. The method according to claim 16, wherein the loading of the agglomerate collecting area (24; 92) and / or the discharge area and / or the reaction area with the oxidizing agent (112) is temporally related to the loading of the agglomerate collecting area (24; 92) and / or the discharge area takes place with filtration aid, in particular the application of the agglomerate collection area (24; 92) and / or the discharge area and / or the reaction area with filtration aid precedes, or upon application of the agglomerate collection area (24; 92) and / or the discharge area and / or the reaction area with filtration aid follows.

18. Filter device (10) for cleaning crude gas carrying foreign bodies, comprising: at least one filter element (14) with at least one filter surface separating a crude gas side from a clean gas side in a crude gas space (15) to which a crude gas stream (44) containing a foreign matter can be fed; an oxidizing agent supply device which is designed to supply an oxidizing agent (112) to a reaction region which is located on the raw gas side of the filter surface downstream of the filter surface; in such a way that foreign bodies contained in the material cleaned from the filter surface and / or the raw gas stream (44) react in the reaction area with the oxidizing agent (112) to form oxide-containing foreign bodies.

19. Filter device (10) according to claim 18, wherein the oxidizing agent is air or an oxygen-containing gas and / or wherein the reaction area is located downstream of the raw gas space (44); and / or wherein an agglomerate collecting area (24; 92) is provided which is designed to receive material cleaned from the filter surface, foreign bodies or agglomerates containing foreign bodies being cleaned off on the filter surface and in the agglomerate collecting area (24; 92 ) intercepted and held; wherein the agglomerate collecting area (24; 92) has a first closure device (96) which is controllable in such a way that it closes off the raw gas space (44) from a discharge area downstream of the raw gas space (44) for the removal of material cleaned from the filter surface or a Establishes a connection between the raw gas space (44) and the discharge area; wherein in particular the discharge area contains the reaction area.

20. The filter device (10) according to claim 18 or 19, wherein an arrangement is provided for feeding a heat transfer fluid to the reaction area and removing the heat transfer fluid after flowing through the reaction area in order to dissipate heat generated during the reaction.

21. Filter device (10) according to claim 19 or 20, wherein the oxidizing agent feed device opens into the discharge area; and / or wherein the discharge area has a second closure device which is arranged downstream of the first closure device (96) in the transport direction of material cleaned from the filter surface.

22. The filter device (10) according to claim 21, wherein the reaction region lies between the first closure device (96) and the second closure device.

23. Filter device (10) according to one of claims 18 to 22, wherein in the reaction area a conveyor element is provided for transporting material cleaned from the filter surface, in particular a conveyor screw, a rotary valve, a gradient and / or a fluidizing device; wherein the conveying element is designed in particular in such a way that a transport direction of material cleaned from the filter surface can be reversed.

24. Filter device according to one of claims 18 to 23, further comprising an exhaust gas outlet region (258) which has a filter unit with at least one filter element and an exhaust gas outlet (218), the exhaust gas outlet region (258) in particular having a compressed gas cleaning device which is designed to to apply compressed air pulses to the at least one filter element; wherein the exhaust gas outlet area (258) is designed in particular so that a mixture (146) of residues formed in particular during the reaction and excess oxidizing agent can be filtered in this and discharged through the exhaust gas outlet (218).

25. Filter device (10) according to one of claims 19 to 24, wherein the discharge area comprises an agglomerate collecting container (92); wherein the agglomerate collecting container (92) in particular comprises the reaction area; and / or wherein at least one element for moving material cleaned from the filter surface is provided in the agglomerate collecting container (92), in particular a screw conveyor, a fluidizing device, a pivoting device for the agglomerate collecting container (92) and / or a mixer.

26. The method according to any one of claims 18 to 25, wherein the reaction area can be heated, in particular heated and / or cooled, and / or wherein the reaction area has an ignition device to start the reaction of foreign bodies with the oxidizing agent (112).

27. Filter device (10) according to one of claims 18 to 26, further comprising a filtration aid input arrangement with one in the raw gas space (15), in the raw gas stream (44) upstream and / or downstream of the raw gas space (15) and / or in the reaction area and / or a filtration aid supply line (82) opening into the agglomerate collecting container (92) for supplying filtration aid and / or an oxidizing agent supply line for supplying oxidizing agent; wherein the filtration aid is configured in such a way that it suppresses a reaction of foreign bodies with oxidizing agents, in particular with oxygen.