Method for dry filtering of a gas flow carrying foreign matter and filter device for cleaning raw gas carrying foreign matter

Abstract

The present invention relates to a method and a filter device for dry filtering a gas flow carrying foreign matter, in particular in a filter device for purifying exhaust gas generated in additive manufacturing technology, the method comprising: introducing a raw gas flow (44) containing foreign matter into a raw gas chamber (15) of a filter unit (12), the filter unit (12) having at least one filter surface separating a raw gas side from a clean gas side; supplying an oxidant to a reaction area (24) located on the raw gas side downstream of the filter surface, so that foreign matter contained in a substance removed from the filter surface and / or in the raw gas flow reacts with the oxidant in the reaction area (24) to form foreign matter containing oxides.

Description

Technical Field

[0001] The invention relates to a method for dry filtering a gas flow carrying foreign matter, and to a filter device for cleaning a raw gas carrying foreign matter. Background Art

[0002] When purging gases carrying highly flammable foreign matter or extraneous matter, such as is done in systems for additive manufacturing of workpieces made of metal (e.g. in laser sintering of workpieces made of titanium or aluminum alloys), there is a risk of uncontrolled fires in the exhaust gas. This risk is particularly great when such highly flammable foreign matter is deposited on the filter surface and accumulates in the process. Similar to the design shown in WO 2012 / 032003 A1, attempts have been made to counteract these risks by pre-coating the filter surface with an inertizing filter aid, such as CaCO 3 , or by adding such an aid to the raw gas to be purified. Summary of the invention

[0003] The object of the invention is to prevent or suppress the combustion of raw gas by means of a dry filter when filtering raw gas containing flammable foreign matter, such as, in particular, when filtering exhaust gas produced in additive manufacturing technology.

[0004] According to the invention, in a method for dry filtering a gas flow carrying foreign matter, which method is used in particular in a filter device for removing exhaust air or waste gas generated in additive manufacturing technology, a raw gas flow containing foreign matter is fed into a raw gas space of a filter unit having at least one filter surface separating a raw gas side from a clean gas side. In addition, an oxidant is fed to a reaction zone on the raw gas side of a filter surface located downstream of the filter surface. The oxidant is fed so that foreign matter contained in the material removed from the filter surface and / or foreign matter contained in the raw gas flow reacts with the oxidant in the reaction zone to form foreign matter containing oxides.

[0005] The invention proposes a method and provides a filter device of corresponding design, in which a spontaneous oxidation of reactive or even highly reactive foreign matter in the exhaust gas, such as metal-containing particles in the exhaust gas from additive manufacturing plants such as laser sintering devices, is particularly induced. The high reactivity of such foreign matter with oxidants such as oxygen or air - which is in fact the reason why dry filtration of such exhaust gases is problematic - is thus particularly used to trigger a spontaneous reaction of the foreign matter with the oxidant. Surprisingly, this spontaneous reaction can be particularly induced and its course kept well controlled by suitable control of the supply and / or discharge of the oxidant and, if necessary, also by other measures, so that uncontrolled reactions of the foreign matter with the oxidant can be avoided. With the method proposed herein, the heat generated during the reaction can be dissipated well, so that there is no need to worry about uncontrolled fires or explosions.

[0006] The basic idea of ​​the invention is not to render the flammable foreign matter contained in the raw gas inert, but to render them harmless by purposefully initiating and carrying out a controlled transfer of these flammable foreign matter into an oxidized configuration, i.e. by chemical reaction. In the oxidized configuration, these foreign matter are generally low-reactive or inert and no longer flammable, so that further handling of these oxidized foreign matter no longer requires any special precautions.

[0007] However, care must be taken to ensure that the spontaneous oxidation reaction is carried out in a controlled manner. This can be achieved by appropriately supplying an oxidant to a predetermined reaction zone containing a substance removed from the filter surface and therefore containing foreign matter and / or further removing the oxide from the reaction zone by measures. It has been found that if the oxidant is not only supplied to the reaction zone, but also flows through the reaction zone, the process of the oxidation reaction, which is often strongly exothermic, can be well controlled. Then, the oxidant is supplied to the reaction zone at a first position or in the first zone (inlet), and flows through the reaction zone until it leaves the reaction zone again at another position or another zone (outlet), in any case, provided that it is not consumed by the reaction with the substance containing foreign matter when flowing through the reaction zone. In this way, in particular, an excess of oxidant can be provided in the reaction zone, because it is necessary to spontaneously initiate the desired reaction for forming foreign matter containing oxide or to maintain the desired reaction in a controlled degree. The oxidant flow flowing through the reaction zone allows the process of the oxidation reaction to be accurately controlled. Once the oxidant flow begins, the oxidation reaction proceeds spontaneously but in a controlled manner and can be well controlled by adjusting the intensity of the oxidant flow, and also by adjusting the composition of the oxidant flow.

[0008] In the case of spontaneous oxidation, the desired reaction to form foreign matter containing oxides occurs substantially without providing activation energy by energy supply from an energy source such as an ignition source or a heat source. Oxidation may have been initiated by contact of the oxidizing agent with substances that were detached from the filter surface during the cleaning process and are present in or enter the reaction zone.

[0009] The oxidant may be air or an oxygen-containing gas. Other substances such as inert gases such as nitrogen or noble gases may be mixed with the oxidant to form an oxidant stream. For example, air may be used to form the oxidant stream, or an oxygen-depleted mixture having an oxygen content of 5-21% by volume. The oxidant or oxidant concentration in the oxidant stream is selected to be sufficiently high to allow spontaneous reaction of the foreign matter-containing material in the reaction zone to form the foreign matter-containing oxide.

[0010] The expression "on the raw gas side of the filter surface located downstream of the filter surface" is intended to express that the reaction zone is downstream of the raw gas space relative to the transport of foreign matter that has accumulated on the filter surface and has been removed from the filter surface during a removal cycle (e.g., by applying a pressure pulse to the filter surface). Thus, the substances removed from the filter surface are transported to the reaction zone. In particular, the reaction zone is separated from the raw gas space, in particular from the downstream of the raw gas space. If the oxidant is first supplied to the downstream of the reaction zone, but not to the raw gas space or the areas upstream of the raw gas space (i.e., these areas remain free of oxidant), the oxidation treatment of the removed foreign matter-containing substances does not affect the process environment for the actual filtering of the raw gas by introducing the oxidant. In particular, this filtering process or the working process of producing the exhaust gas to be filtered can occur under mostly inert conditions and is not disturbed by the oxidation treatment. When the oxidant is supplied, by temporarily separating the reaction zone from the raw gas space, in particular by separating the raw gas space in an airtight manner, the maintenance of the inert environment in the raw gas space can be additionally ensured.

[0011] As explained, advantageously, when the substances removed from the filter surface react together with the oxidant, the unconsumed oxidant is actively removed from the reaction zone. In this way, a suitable excess oxidant can be provided and a controlled progression of the oxidation reaction can therefore be achieved. This means that the purpose is not necessarily to remove only the reaction products formed during the reaction, particularly foreign matter containing oxides and, where applicable, unconverted or incompletely converted removed substances, from the reaction zone after a more or less complete chemical conversion has occurred. On the contrary, during the course of the oxidation reaction, any oxidant that is not consumed in the reaction should be removed, typically to the same extent as that of adding new oxidant. In this way, the oxidation reaction in the reaction zone can be carried out substantially under constant ambient conditions, particularly at a constant concentration of oxidant.

[0012] Once in the reaction zone or at least in the partial area belonging to the reaction zone, a sufficient proportion of the material containing foreign matter has been converted into foreign matter containing oxide, and / or a sufficiently large amount of the material containing foreign matter has been removed from the reaction zone or at least from the partial area belonging to the reaction zone, it can be considered that the oxidation reaction stops at least in the partial area belonging to the reaction zone. In this case, stop supplying other oxidants to the reaction zone or the partial area belonging to the reaction zone. Then, reaction products or reaction residues are usually removed from the reaction zone or the partial area belonging to the reaction zone. It is generally considered that substantially all reaction products or reaction residues are removed from the reaction zone or the partial area belonging to the reaction zone. It is also sufficient to remove only a part of the reaction product or reaction residue. The reaction product or reaction residue remaining in the reaction zone or the partial area belonging to the reaction zone can be subsequently oxidized together with the new material entering the reaction zone or the partial area belonging to the reaction zone, if necessary, after adding other oxidants. After the oxidant still remaining in the reaction zone or the partial area belonging to the reaction zone after the reaction has stopped or has occurred is removed, the reaction zone or the partial area belonging to the reaction zone can be made to communicate with the raw gas space fluid without the risk of oxidant entering the raw gas space.

[0013] In particular, the oxidant can be sucked or drawn out of the reaction area or a part of the reaction area. For this purpose, the reaction area can be subjected to a negative pressure in order to suck out the oxidant still present in the reaction area from the reaction area. It is also possible to suck out the reaction products and / or other reaction residues from the reaction area by applying a negative pressure to the reaction area. Applying a negative pressure to the reaction area can take place during and / or after the reaction of the substances removed from the filter surface with the oxidant.

[0014] An oxidant inlet may be provided for supplying the oxidant to the reaction zone or a sub-region belonging to the reaction zone. An oxidant outlet may be provided for removing the oxidant from the reaction zone or a sub-region belonging to the reaction zone. In the simplest case, the oxidant inlet may also simultaneously serve as an oxidant outlet. However, it is generally provided that the oxidant outlet is different from the oxidant inlet, in particular such that an oxidant flow is formed between the oxidant inlet and the oxidant outlet, which oxidant flow crosses the reaction zone or a sub-region belonging to the reaction zone as largely as possible.

[0015] The oxidant outlet can be a specially provided outlet for the discharge of gases, in particular oxidants. However, the oxidant which has not yet been consumed is discharged through the oxidant outlet together with foreign matter containing oxides which has been formed during the reaction, if applicable, and scavenged substances which have not yet reacted. In this case, the oxidant outlet is designed to discharge both gaseous substances and substances containing solids.

[0016] It is conceivable, but not absolutely necessary, that all reactions of the material containing foreign matter with the oxidant occur in the upstream region of the oxidant outlet. Except that the oxidant stream may be recycled to the oxidant inlet, the oxidant or the mixture of oxidant and other (e.g., inert) fluids discharged by the oxidant outlet is then no longer used for further oxidation. However, it is also conceivable that the reaction zone includes a region located downstream of the oxidant outlet, particularly a pipeline or pipeline, a conveyor and / or a container located downstream of the oxidant outlet. Whether the unconsumed oxidant is discharged together with the foreign matter containing the oxide formed in the reaction process and the foreign matter that may not yet be converted or reacted by the oxidant outlet, this will be particularly worthy of consideration.

[0017] In one possible embodiment, the oxidant outlet can be connected to a pneumatic conveying device. In particular, the pneumatic conveying device can be a conveying device operating as a solid injector or a jet pump. Alternatively, a suction blower can be conceived. The pneumatic conveying device can be connected to the oxidant outlet via a conveying connection and thus exert a suction action on the reaction zone or a portion of the reaction zone. The suction action causes the oxidant or a mixture of the oxidant and other (e.g., inert) fluids introduced into the reaction zone or a portion of the reaction zone to flow toward the oxidant outlet as an oxidant, thereby passing through the reaction zone or a portion of the reaction zone and causing the oxidant to react with the substance containing foreign matter to form foreign matter containing oxides.

[0018] The foreign matter containing oxide formed in the reaction process and the foreign matter that may not react can also be discharged via a pneumatic conveying device, especially as a conveying device operated by a solid injector or a jet pump. The pneumatic conveying device can also be used for example to further transport this solid-containing material to a collection container or a disposal container by a pipeline. The solid-containing material transported can include the foreign matter containing oxide produced by the reaction with the oxidant, or the material of the removal that has not reacted. The pneumatic conveying device can be particularly configured to remove the solid-containing material from the reaction zone or the partial area of ​​the reaction zone. However, it can also be imagined that the pneumatic conveying device is set to extract the solid-containing material from the reaction zone or the partial area of ​​the reaction zone and to extract the gaseous material from the reaction zone or the partial area of ​​the reaction zone and / or to add the oxidant to the solid-containing material transported. For example, in the solid injector, a fluid or an oxygen-containing gas mixture containing an oxidant such as air can be used as a transport fluid. In this manner, as the transport fluid and transport solids-containing mixture is conveyed through the downstream portion of the solids injector of the transport line, the mixing of the transport fluid and the transport solids-containing material causes the desired oxidation reaction to occur efficiently.

[0019] By controlling the pneumatic conveying device, the suction intensity acting on the material in the reaction zone or the partial area of ​​the reaction zone can be adjusted. Under lower suction intensity, (at least substantially) only gaseous material is extracted from the reaction zone or the partial area of ​​the reaction zone, so that the opening (suction opening) of the conveying connection piece connected to the pneumatic conveying device forms an oxidant outlet. Under the situation of stronger suction intensity, both the material containing solid and the gaseous material are extracted from the reaction zone or from the partial area of ​​the reaction zone. In this case, the suction opening is formed for further conveying the material containing solid in the reaction zone or in the partial area of ​​the reaction zone, and at the same time, the oxidant outlet and / or arrangement for supplying oxidant to the material containing solid further conveyed is formed. The latter is for example by mixing the conveying fluid containing oxidant in the solid injector with the material containing solid.

[0020] In addition, the reaction zone or the partial region of the reaction zone is subject to an inert fluid, particularly an effect of an inert gas. By mixing inert gases, for example, the concentration of the oxidant in the oxidant stream can be appropriately adjusted, if necessary, the process of the oxidation reaction can be accelerated or slowed down. Using an inert fluid that does not contain an oxidant, the effect on the reaction zone or the partial region of the reaction zone can be used for example to stop the further reaction process of the material and the oxidant removed in the reaction zone or the partial region of the reaction zone. Inert fluid can also be used to remove any remaining oxidant in the reaction zone or the partial region of the reaction zone, to produce enough inert atmospheres in the reaction zone or the partial region of the reaction zone, to allow the formation of fluid contact between the reaction zone or the partial region of the reaction zone and the raw gas space. For example, the reaction can be stopped after a certain amount of the removed material has reacted with the oxidant or after a certain proportion of the removed material has reacted with the oxidant.

[0021] For example, it can be provided that the reaction of the substance removed from the filter surface with the oxidant is carried out in a reaction phase, wherein the oxidant is applied to the reaction zone or a portion of the reaction zone, which occurs during the corresponding reaction phase, and after the corresponding reaction phase, the reaction zone or a portion of the reaction zone is subjected to the inert fluid without the addition of the oxidant. In this way, the reaction process can be managed in a very controlled manner, because the reaction will stop after the oxidant supply is cut off, and then, any substance in the reaction zone or a portion of the reaction zone, whether solid or gas, can be removed from the reaction zone or a portion of the reaction zone in whole or in part. By simultaneously flushing the reaction zone or a portion of the reaction zone with an inert fluid, the concentration of the oxidant can then be reduced to the extent that fluid contact between the reaction zone or a portion of the reaction zone and the raw gas space becomes possible again, without the risk of the oxidant entering the raw gas space. Then, the reaction zone or a portion of the reaction zone is ready to receive another batch of substances removed from the filter surface.

[0022] The introduction of an inert gas into the reaction zone or a part of the reaction zone can be achieved in a simple manner, for example by supplying an inert fluid to the solid injector via a purge port thereof.

[0023] In order to support the described measures, it can be provided that the inert fluid is supplied to the reaction region or a part of the reaction region via an additional fluid inlet which is different from the oxidant inlet. For example, such an additional fluid inlet can be arranged in the vicinity of an opening connecting the reaction region or a part of the reaction region with the raw gas space, so that the oxidant can be selectively flushed out from the vicinity of this opening. It is also conceivable to provide a plurality of such additional fluid inlets.

[0024] It may also be advantageous if the inert fluid and / or the oxidant is discharged from the reaction region or a part of the reaction region via one or more further outlets provided in addition to the oxidant outlet. For example, it may be provided that a plurality of oxidant outlets distributed on a housing surrounding the reaction region or a part of the reaction region are arranged so that a widely distributed oxidant flow which adequately covers the volume of the reaction region is distributed over the reaction region or a part of the reaction region. It may also be provided that a specific arrangement of one of the several outlets for the inert fluid relative to the corresponding connected inlet opening for the inert fluid is provided in order to flush the oxidant out of certain areas of the reaction region or the part of the reaction region in a particularly effective manner.

[0025] When the reaction of the substances removed from the filter surface with the oxidant occurs, the application of an inert fluid to the reaction zone or part of the reaction zone may already have begun. In particular, the inert fluid can then also be used to remove heat. This is often the case, for example, when the oxidant stream is a mixture of an oxidant (e.g., oxygen) and an inert gas (e.g., nitrogen) containing only a small amount of oxidant.

[0026] The reaction zone or a portion of the reaction zone may be passed through by a heat transfer fluid for removing the heat generated during the reaction of the material removed from the filter surface with the oxidant. In appropriate cases, the heat transfer fluid stream may flow through the reaction zone or a portion of the reaction zone together with the oxidant stream. The oxidant itself may also serve as a heat transfer fluid, particularly when the oxidant is only partially reacted, because an excessive amount of the oxidant is added to accelerate the reaction. The heat transfer fluid may also serve as an inert fluid for flushing out the oxidant that still exists after the reaction from the reaction zone or from the portion of the reaction zone has been completed. It may then be convenient to use an inert fluid without the addition of an oxidant as a heat transfer fluid.

[0027] The reaction zone may comprise an agglomerate collection area, which is adapted to receive the material removed from the filter surface, whereby foreign matter or agglomerates containing foreign matter that have accumulated on the filter surface are removed and collected and retained in the agglomerate collection area. The agglomerate collection area then in particular constitutes a partial area of ​​the above-mentioned reaction zone. The agglomerate collection area can be designed so that the material removed from the filter surface falls directly from the raw gas space into the agglomerate collection area without having to be previously collected at a location between the filter element and the agglomerate collection area (e.g., in the bottom area of ​​the filter housing surrounding the raw gas space).

[0028] The agglomerate collection area may have a first closing device with a first shut-off member connected thereto. The first closing device may be designed such that it enables material falling from the filter surface during the cleaning process to be collected in the agglomerate collection area (in particular only briefly), and after the cleaned material has been collected in the agglomerate collection area, the reaction area is closed from the raw gas space (in particular the reaction area is closed in a gas-tight manner), at least until the concentration of the oxidant in the reaction area has dropped to a sufficient extent.

[0029] Reduced to a sufficient degree means, in particular, until it can be assumed that the concentration of the oxidant in the reaction zone has been reduced to below a predetermined threshold value. When the reaction forming the foreign matter containing the oxide has completely occurred, the oxidant has been consumed in large quantities and / or all materials have been removed from the reaction zone or the agglomerate collection area, the situation may be so. In fact, as long as the rate at which the reaction is carried out is fully known (for example, from a test), it can be assumed that this state is reached by waiting for a predetermined time from the start of the oxidation reaction. However, usually, when after the reaction has been completed, especially by suction and / or sucking out with an inert fluid, the oxidant has been removed from the reaction zone or the agglomerate collection area, this condition will be reached in any case.

[0030] In particular, the first cut-off member can be designed so that when the first cut-off member is opened, the receiving material removed from the filter surface in the agglomerate collection area will not be significantly hindered in any case. In particular, the first cut-off member is opened immediately during and / or after the removal of the filter element, and in any case remains open until the material that falls off the filter surface on the raw gas side during the removal process has been substantially collected in the agglomerate collection area. In particular, after the reaction for forming foreign matter containing oxides in the reaction area has been completed, once the concentration of the oxidant in the reaction area has dropped to a sufficient degree, and there is no longer any reason to worry that the oxidant will enter the raw gas space from the reaction area to the extent that it will interfere with the process conditions prevailing there, the first cut-off member can be opened again.

[0031] The material removed from the filter surface can be transported from the agglomerate collection area to a downstream discharge area. The discharge area can be located downstream of the reaction area, in the sense that no further oxidation of the foreign matter occurs in the discharge area itself. However, it is conceivable, and in fact preferred, that the reaction area also at least partially comprises the discharge area and that, depending on the presence of the oxidant, the foreign matter is still oxidized in the discharge area. In this case, the oxidant can be supplied not only to the agglomerate collection area, but also to the discharge area or even exclusively to the discharge area.

[0032] The discharge region may have a second closure device having a cut-off member which can cut off the discharge region from the downstream region, in particular in an airtight manner. The second closure device is not absolutely necessary, in particular if the purpose is to achieve a complete conversion of most of the combustible foreign matter into foreign matter containing oxides before the material introduced into the discharge region reaches the downstream end of the discharge region. In the absence of the second closure device, or when the second closure device is open, the desired oxidation reaction in the discharge region can take place very effectively while rapidly conveying the transported material forward. When the second closure device is provided, the connected cut-off member can be designed to form an airtight partition in its closed position. However, this feature is also not crucial; in many cases, only the cut-off function for particles greater than a certain size will be effective. In particular, the reaction zone can be located between the first closure device and the second closure device. The discharge region may further include a collecting container. In the collecting container, solid-containing material, in particular oxide-containing products from the oxidation of the material removed from the filter surface, can be collected and eventually disposed of.

[0033] After leaving the reaction zone, particularly when reaching the downstream portion of the discharge zone, any oxidant that is not consumed in the reaction zone and, if applicable, any other fluid produced as excess fluid or waste liquid (particularly in the case of gaseous fluid, as waste gas) returns to the reaction zone in whole or in part and can be useful. For example, a waste liquid outlet or a waste gas outlet can be connected with a collecting container, and the fluid stream leaving the waste liquid outlet can be returned or recycled to the reaction zone completely or in part. In particular, the fluid recycling of the type mentioned here can significantly limit the amount of the fluid consumed, whether as an oxidant, a heat transfer fluid, a cleaning fluid and / or a transport fluid. In particular, an inert fluid is usually not consumed in the process of conveying through the reaction zone, and can be kept indefinitely in the loop formed in this way. If necessary, fresh oxidant can be added to the recirculating fluid stream to compensate for the oxidant consumption in the reaction zone.

[0034] If a recirculation of the fluid is provided, in particular, a control / regulation system can be provided, which is designed so that the fluid pressure in the loop, in particular in the reaction zone, does not exceed and / or does not fall below a predetermined value, in particular remains within a predetermined range. As a control variable for controlling the fluid pressure, it can be provided that, for example, only a portion of the fluid flow accumulated as waste liquid is returned to the reaction zone, while another portion is discharged to the environment or an external waste liquid treatment system, the returned fluid flow is always regulated so that the fluid pressure in the loop, in particular in the reaction zone, remains constant, in particular does not exceed a predetermined value and / or does not fall below another predetermined value, in particular remains within a predetermined range.

[0035] In the reaction zone, a conveying member can be provided for conveying the material removed from the filter surface. Preferably, the conveying member can be a conveying fluid. For example, when a solid injector is provided, for removing material from the agglomerate collection container to the discharge line, the fluid for generating negative pressure or vacuum at the conveying port of the solid injector can serve as a conveying fluid for further conveying the material conveyed from the agglomerate collection container downstream of the solid injector. The conveying member can be used for further fast and effectively conveying the material containing solid. In addition, the conveying member can improve the mixing or looseness of the material containing solid, so that this material is more easily contacted with an oxidant. Alternatively or additionally, the conveying member can also include a screw conveyor, a rotary valve, an inclination or an inclined plane and / or a fluidizing device. In particular, the conveying member can be designed so that the conveying direction of the material removed from the filter surface can be reversed.

[0036] Other embodiments of the above method and the filter device described in further detail below are described below:

[0037] The reaction zone may comprise a collecting container. At least one means for moving the material removed from the filter surface may be arranged in the collecting container, in particular a screw conveyor, a fluidizing device, a pivoting device and / or a mixer for the collecting container.

[0038] The reaction zone can be designed to be temperature-controlled, in particular heated and / or cooled. Different from the above, multiple designs can be conceived in which ignition devices and / or heating devices are assigned to the reaction zone in order to actively start the reaction of foreign matter with the oxidant. Then, the conversion of the removed substances to form foreign matter containing oxides does not depend on the start of spontaneous oxidation. In all other aspects, the above and the above also apply to this alternative embodiment of the present invention. The applicant reserves the right to direct claims to such alternative embodiments, for example in the form of divisional applications.

[0039] The foreign matter may, for example, contain or be a metal and have a granular, in particular flaky, powdery or fumed configuration. In particular, the foreign matter may have an incompletely oxidized or even completely non-oxidized configuration. In particular, the foreign matter may be titanium powder or titanium flakes. The foreign matter may not be an oxidized metallic foreign matter or an incompletely oxidized metallic foreign matter. For example, such foreign matter is produced during the additive manufacturing of metal workpieces by using powdered metallic substances when the workpieces are built up layer by layer from a powder bed. Typical metals used in this method which can lead to combustible foreign matter in the exhaust air are titanium, aluminum, magnesium and their alloys, as well as various steels such as structural steels, quenched and tempered steels, and high-alloy stainless steels.

[0040] The method may further include the step of adding a filter aid to the raw gas stream, the filter surface, the reaction zone, and / or the discharge zone. The filter aid may be configured to inhibit the reaction of foreign matter and / or substances removed from the filter surface with an oxidant, particularly oxygen. If necessary, a flame retardant auxiliary material may be added to the exhaust gas so that agglomerates of foreign matter and filter aid are formed. The addition of SiO2-based filter aids has proven to be particularly suitable for inhibiting the combustion of raw gas in additive manufacturing processes using titanium and / or aluminum-magnesium alloys. For example, laser sintering methods are known as additive manufacturing processes that produce exhaust gases that tend to self-ignite.

[0041] The filter aid can be, for example, an inorganic substance, in particular, a silicon oxide-based inorganic substance or a calcium carbonate-based inorganic substance can be used as a filter aid. In particular, the filter aid can be used to ensure that the oxidation occurring in the reaction zone does not get out of control.

[0042] When added, the filter aid can have a granular, in particular powdered configuration. This allows accurate metering of the filter aid into the raw gas stream and / or into the filter device, in particular for coating the filter surface (pre-coating). In addition, suitable filter aids allow the use of simple supply mechanisms, such as flap valve supply or pressurized gas supply. When fine-grained filter aids are added, the flame-retardant agglomerates are formed more efficiently.

[0043] The filter aid can be configured to bind metal-containing foreign bodies in agglomerates in a particle configuration, in particular at temperatures of 600° C. or higher, in particular at temperatures of 650° C. or higher, in particular at temperatures of 1220° C. or higher, in particular at temperatures of 750° C. or higher, in particular at temperatures of 1320° C. or higher. Depending on the filter 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 the agglomerates to an undesirably large extent. The agglomerates formed are non-flammable or only have a flame retardancy in the temperature range mentioned, so that a higher operating safety is possible compared to conventional filter devices. Many SiO2 glasses begin to soften at temperatures starting at 600° C. and can then form agglomerates with foreign bodies. Depending on the configuration of the SiO2 substance, for example by adding additives or forming it into a glass foam, the temperature at which softening begins can be varied in a suitable manner.

[0044] Agglomerates mixed with filtering aids can become a flowable configuration similar to a glass melt when heated strongly, and become a glassy configuration after cooling to below the glass transition point. The filtering aid melts and thereby captures foreign matter in the melt, so that inertization has already occurred in this state. Once the melt solidifies, a glassy or glassy configuration is formed. The formation of a flowable configuration can occur in particular after heating to a temperature of 600° C. or more, in particular 650° C. or more, in particular 1220° C. or more, in particular 750° C. or more, in particular 1320° C. or more. In the process, the agglomerates can have a glassy configuration after cooling to below the glass transition temperature. This can prevent the oxidant from coming into contact with foreign matter containing metals.

[0045] In particular, the filter aid may be a substance which has a glassy structure or which can be converted into a glassy structure under the influence of heat.

[0046] Silicon dioxide-based substances with a glassy configuration are made of solids and have an amorphous structure or at least a partially crystalline structure. Such glasses have silicon dioxide as their main component and their network structure is mainly formed by silicon dioxide. In particular, such glasses include so-called silicate glasses. Silicate-based glasses can exist in pure form, for example as silica glass. If a higher softening temperature is desired, quartz glass is also conceivable. In addition to silicate-based glasses, other components may be present, such as phosphates, borates, etc.

[0047] The filter aid may have at least one of the following substances as a main component: expanded glass beads, glass powder, silicon dioxide particles (SiO2 particles), quartz powder or a mixture of at least two of these substances. In particular, very suitable glass substances are those made from recycled waste glass (recycled glass), such as expanded glass or foamed glass. Expanded glass is produced by grinding discarded broken glass and adding a binder and / or an expander thereto. This produces roughly round grains with small gas-filled pores. Expanded glass with a grain size of 0.04-16 mm can be produced. These particles have a closed pore structure. Foamed glass, in particular foamed glass ballast, is produced in a similar manner. Glass or foamed glass can be produced so that the temperature at the beginning of the softening range and / or the lower limit of the glass transition temperature takes a value between 600° C. and 750° C.

[0048] In the event of a fire, the initially formed agglomerates of filter aid and metal powder, which are still powdery or granular, soften or melt under the action of heat. The flowable glass melt surrounds the foreign matter containing metal and makes them inert. After the melt solidifies, a glassy structure is formed, in which the foreign matter containing metal is permanently enclosed in the filter aid or surrounded by the filter aid. Once a flowable configuration is formed, the individual self-igniting particles of the metal are bound (vitrified) by the filter aid. In the vitrified state, it is difficult or impossible to react with an oxidant, especially with oxygen (O2). In particular, the vitrification process of the type described occurs at those locations where agglomerates of filter aid accumulate. In particular, when heat is generated (for example in the event of a fire), the filter cake that has been formed on the raw gas side on the filter surface and is also completely or in any ratio mainly composed of agglomerates of filter aid can present such a phase transition from a powdery or granular configuration to a flowable and ultimately to a glassy configuration. This vitrification process can also take place at the surface of the bulk cone formed in the agglomerate collection area during operation, resulting in effective inertization of the material contained in the agglomerate collection area. This vitrification process can be assisted by coating the surface of the bulk material cone formed in the agglomerate collection area with a layer of filter aid from time to time.

[0049] The agglomerates formed can remain chemically stable in the event of a fire, i.e. in the presence of an oxidant (typically oxygen), at temperatures up to 650°C, in particular up to 750°C, in particular up to 850°C, in particular up to 1000°C, in particular up to 1250°C, in particular up to 1500°C.

[0050] The filter aid can also have a gaseous configuration. In this case, the filter aid can also be used as a heat transfer fluid after oxidation of foreign matter and / or substances removed from the filter surface has occurred.

[0051] When the filter element has been cleaned and the material cleaned from the filter surface has been deposited in the agglomerate collection area and / or discharge area and / or reaction area, the filter aid and / or oxidant can be used to act on the agglomerate collection area and / or discharge area and / or reaction area.

[0052] The application of the oxidant to the agglomerate collection area and / or the discharge area and / or the reaction area can be carried out in a timed relationship with the application of the filtering aid to the agglomerate collection area and / or the discharge area, in particular before the application of the filtering aid to the agglomerate collection area and / or the discharge area and / or the reaction area, or after the application of the filtering aid to the agglomerate collection area and / or the discharge area and / or the reaction area.

[0053] The filter device for cleaning raw gas carrying foreign matter according to the present invention comprises at least one filter element having at least one filter surface in the raw gas space, to which the raw gas flow containing foreign matter can be supplied. In addition, an oxidant supply device is provided, which is suitable for supplying an oxidant to a reaction zone on the raw gas side of the filter surface located downstream of the filter surface. The oxidant supply facility is designed so that foreign matter contained in the material removed from the filter surface and / or in the raw gas flow reacts with the oxidant in the reaction zone to form foreign matter containing oxides.

[0054] The explanations given above with reference to the method according to the invention also apply analogously to the filter device according to the invention. In order to avoid repetitions, the previous explanations are specifically mentioned.

[0055] In particular, the oxidant may be air or an oxygen-containing gas. In particular, the reaction zone may be located downstream of the raw gas space. In particular, the reaction zone may be adapted to be cut off relative to the raw gas space when the oxidant is supplied. These measures help ensure that the raw gas space remains substantially free of oxidant.

[0056] The filter device can be designed so that, during the reaction of the material removed from the filter surface with the oxidant, unconsumed oxidant can be removed from the reaction zone. This can achieve particularly good control of the reaction occurring in the reaction zone.

[0057] The filter device can have an oxidant inlet and an oxidant outlet, wherein the oxidant inlet is designed to supply oxidant to the reaction zone or a part of the reaction zone, and the oxidant outlet is designed to discharge oxidant from the reaction zone or a part of the reaction zone, and the oxidant outlet is particularly different from the oxidant inlet.

[0058] The filter device can further be configured to discharge, in particular to suck away, unconsumed oxidant through the same oxidant outlet as the oxide-containing foreign matter formed during the reaction (and, if applicable, as yet unreacted foreign matter).

[0059] The reaction zone may include the area downstream of the oxidant outlet, in particular a downstream pipeline, conveyor and / or container.

[0060] It is particularly suitable when the oxidant outlet is connected to a pneumatic conveying device, in particular to a conveying device operating as a solid injector or jet pump and / or to an exhaust fan. The filter device can also have a pneumatic conveying device, in particular a conveying device operating as a solid injector or jet pump, which is arranged to discharge foreign matter containing oxides formed during the reaction and any foreign matter that has not yet reacted. The pneumatic conveying device can also be used to remove oxidants or other gaseous substances from the reaction area or from parts of the reaction area.

[0061] The filter device can be designed to apply negative pressure to the reaction area or part of the reaction area, in particular during and / or after the reaction of the substances removed from the filter surface with the oxidant. Additionally or alternatively, the filter device can be configured to act on the reaction area or part of the reaction area with an inert fluid, in particular, with an inert gas.

[0062] The filter device can also have a control system, which is arranged so that the reaction of the substances removed from the filter surface with the oxidant takes place in a reaction phase, wherein during the reaction phase it is arranged to apply oxygen to the reaction zone or a part of the reaction zone, and / or after the corresponding reaction phase, an inert fluid without added oxidant is applied to the reaction zone or a part of the reaction zone.

[0063] The filter device may have a further fluid inlet into the reaction zone or a part of the reaction zone, different from the oxidant inlet, for introducing an inert fluid.

[0064] The filter device may comprise, in addition to the oxidant outlet, further outlets for discharging the inert fluid and / or the oxidant from the reaction zone and / or from parts of the reaction zone.

[0065] In any case, after the reaction of the substances removed from the filter surface with the oxidant has occurred, the reaction zone or a part of the reaction zone can be subjected to an inert fluid, in particular an inert gas, and / or a negative pressure. In this case, the inert fluid displaces the oxidant from the reaction zone or from a part of the reaction zone, so that uncontrolled oxidation no longer occurs. This effect can also be achieved by applying a negative pressure to the reaction zone or a part of the reaction zone, that is, the oxidant is sucked away or withdrawn from the reaction zone or a part of the reaction zone. In this respect, the two measures can also be combined and support each other.

[0066] The filter device may further comprise an oxidant inlet, via which the oxidant can be supplied to the reaction zone or a portion of the reaction zone. The oxidant inlet may be provided with a shut-off device to allow the oxidant to enter the reaction zone or a portion of the reaction zone in a controlled manner. The filter device may also have an outlet, in particular an outlet different from the oxidant inlet, through which oxidant still present in the reaction zone or a portion of the reaction zone can be discharged after the reaction of the substances removed from the filter surface with the oxidant has occurred.

[0067] Preferably, the oxidant inlet may be arranged at the top end of the reaction region or a part of the reaction region, which is arranged on the side of the reaction region or the part of the reaction region facing the raw gas space. In particular, the outlet may be arranged at the bottom end of the reaction region or the part of the reaction region, which is arranged on the side of the reaction region or the part of the reaction region facing away from the raw gas space. This arrangement allows the oxidant to be efficiently and reliably supplied to the reaction region, and also allows the substances removed from the filter surface to be reliably emptied from the reaction region or the part of the reaction region through the outlet together with the oxidant flow.

[0068] The filter device can also be provided with a common outlet, through which residues of the reaction of the substances removed from the filter surface with the oxidant, in particular formed foreign matter containing oxides, completely or partially unreacted substances and excess oxidant can be removed from the reaction area or from parts of the reaction area. This leads to a simple structure of the filter device, in particular a simple structure of the reaction area. The reaction area or parts of the reaction area can have a heat transfer fluid flowing through it for removing the heat generated during the reaction.

[0069] The reaction area may also include an agglomerate collection area, which is designed to receive material removed from the filter surface, whereby foreign matter or agglomerates containing foreign matter that have accumulated on the filter surface after removal can be collected and stored in the agglomerate collection area. Then, in particular, the agglomerate collection area constitutes a partial area of ​​the above-mentioned reaction area.

[0070] The agglomerate collection area can have a first closure device connected to it, which has a first shut-off member and is designed so that material that has fallen off the filter surface during the cleaning process can be collected in the agglomerate collection area, in particular only briefly, and after the cleaned material has been collected in the agglomerate collection area, the reaction area is in any case cut off from the raw gas space, at least until the concentration of the oxidant in the reaction area has dropped to a sufficient extent.

[0071] Furthermore, the filter device may have a discharge region downstream of the agglomerate collection region, into which substances removed from the filter surface may be transported, in particular, the reaction region includes at least a portion of the discharge region, and specifically, an oxidant may be supplied to the agglomerate collection region and / or the discharge region.

[0072] The discharge region can have a second closing device, wherein in particular the reaction region is arranged between the first closing device and the second closing device.

[0073] In the reaction area, a transport member can be provided, which is configured to transport the material removed from the filter surface, wherein specifically, the transport member includes a transport fluid. For example, when the solid injector is configured to discharge the material from the agglomerate collection container into the discharge line, the fluid used to generate negative pressure at the transport port of the solid injector can serve as a transport fluid for further transporting the material transported from the agglomerate collection container downstream of the solid injector.

[0074] With regard to advantages and benefits of the individual features, reference is made to the description of the method and other features according to the invention.

[0075] The oxidant may be air or an oxygen-containing gas, in particular an oxygen-containing gas having an oxygen content of 1 to 21% by volume. In the reaction zone, the oxidant is able to spontaneously react foreign matter and / or substances removed from the filter surface. The reaction zone may be located downstream of the raw gas space.

[0076] The filter device may be arranged to supply a heat transfer fluid to the reaction zone and to discharge the heat transfer fluid after flowing through the reaction zone or a portion of the reaction zone to remove heat generated during the oxidation process as well as foreign matter containing oxides and excess oxidant.

[0077] A conveying member, in particular a screw conveyor, a rotary valve, an inclination or an inclined plane and / or a fluidizing device, for conveying the material removed from the filter surface can be arranged in the reaction zone. In particular, the conveying member can be designed to make the transmission direction of the material removed from the filter surface reversible. In particular, the conveying member can be a pneumatic conveying facility, such as a solid injector.

[0078] The discharge area may include a waste liquid outlet area, through which the fluid material produced after passing through the process can be discharged. If the material removed from the filter surface is oxidized by means of a gaseous fluid as described herein, especially by means of a gaseous oxidant, a heat transfer fluid, a cleaning fluid and / or a transport fluid, the gaseous effluent (waste gas) will be mainly produced in the waste liquid outlet area. In the present application, the term "waste gas" or "waste gas outlet area" is also used for simplification, regardless of whether the fluid accumulated at the end of the process is mainly gaseous or liquid. The waste gas outlet area may have a filter unit and a waste gas outlet with at least one filter element. In particular, the waste gas outlet area may include a pressurized gas removal device. The pressurized gas removal device may be configured to apply a pressure pulse to at least one filter element. Alternatively, the filter unit may have at least one filter element with a storage filter. The waste gas outlet area may be designed so that a mixture of residue and excess oxidant formed in particular during the reaction process may be filtered therein and discharged from the filter device through the waste gas outlet.

[0079] In particular, the filter device can have a fluid recirculation unit, which is designed so that after leaving the reaction zone, the unconsumed oxidant in the reaction zone and, if applicable, the further fluid accumulated as waste liquid or waste gas is returned completely or partially into the reaction zone. In particular, a control / regulation system can be provided, which is designed so that the fluid pressure in the resulting circuit, in particular in the reaction zone, does not exceed a predetermined upper limit value and / or does not fall below a predetermined lower limit value, in particular remains within a predetermined range.

[0080] The discharge area can include a collecting container for solid-containing substances, wherein solid-containing substances, in particular foreign matter containing oxides, can be collected. Once the collecting container is filled, the collecting container can be removed by the operator and replaced with an empty collecting container. Thus, interruptions of the filtering process can be avoided. In particular, the discharge area can include a collecting container for isolating solid-containing substances, the collecting container having an outlet (exhaust gas outlet) for fluids, in particular gaseous substances. In this case, the outlet can have a filter unit connected thereto for cleaning the fluid substance from foreign matter of the above-mentioned type. In addition, a fluid recycling unit of the above-mentioned type can be connected to the outlet.

[0081] An arrangement for temperature control, in particular for heating and / or cooling the reaction zone or a portion of the reaction zone, may be coupled to the reaction zone or a portion of the reaction zone. In an alternative embodiment, the reaction zone or a portion of the reaction zone may include an ignition device and / or a heating device for actively initiating the reaction of the foreign body with the oxidant.

[0082] Furthermore, the filter device can comprise a filter aid supply arrangement having a filter aid supply line which opens into the raw gas space, into the raw gas flow upstream and / or downstream of the raw gas space, and / or into the reaction region and / or into the discharge region, in particular into the collecting container, for supplying filter aid. Thus, the filter aid can be configured to inhibit further reactions of foreign matter with oxidants, in particular with oxygen, once a first oxidation of the substances removed from the filter surface has occurred. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The invention and specific embodiments of the invention will be explained in more detail below by means of exemplary embodiments.

[0084] Figure 1 A side view of a filter device according to the invention is shown.

[0085] Figure 2 Relative to Figure 1 The side view rotated 90 degrees shows Figure 1 Filters.

[0086] Figure 3 A schematic diagram of an embodiment of a reaction zone is shown.

[0087] Figure 4 A schematic diagram of another embodiment of a reaction zone is shown.

[0088] Figure 5 A schematic diagram of another embodiment of a reaction zone is shown.

[0089] Figure 6 A schematic diagram of an exemplary discharge area, in particular a collecting container for solids-containing material, is shown. DETAILED DESCRIPTION

[0090] Figure 1 and Figure 2 A filter device 10 for cleaning a raw gas carrying foreign matter according to an embodiment of the present invention is shown in a side view rotated 90 degrees relative to each other. The filter device 10 comprises a filter unit 12 (in Figure 1 Not shown in Figure 2). The filter unit 12 is mounted above a raw gas inlet opening 16 in an upper portion of a housing 18, the raw gas inlet opening 16 being partially omitted for clarity. The filter unit 12 includes a plurality of filter elements 14 in the form of dry filters, each of the filter elements 14 being configured as a rigid body filter. This is intended to indicate that the walls of the filter elements 14 have sufficient rigidity to keep the filter elements 14 upright without the aid of other supporting structures. In this sense, the filter elements 14 are inherently stable. The filter elements 14 are suspended on a common holder extending horizontally and extend parallel to each other in the vertical direction. This is in Figure 2 As schematically shown in Figure 2 One of the filter elements 14 is shown approximately in its installed position. It should be noted that different installations of the filter elements 14 in the housing 18 are also possible, such as a horizontal installation, in which the filter elements extend in the horizontal direction and are attached to vertical holders. Each of the filter elements 14 has at least one filter surface on which the raw gas acts. Figure 1 and Figure 2 In the embodiment, the filter surface on which the raw gas acts is located on the outside (raw gas side) of one of the corresponding filter elements 14. The purified gas flows from the raw gas side to the clean gas side after passing through the wall of the filter element 14, and the purified gas faces the inner space surrounded by the wall of the filter element 14. The filter element 14 is open toward the top so that the clean gas space 17 extends from the inner space to the area above the filter unit 12.

[0091] exist Figure 1 and Figure 2 In the lower region 18b shown in FIG. 1 , the housing 18 takes the form of a funnel with a side wall tapering downward. Adjacent to the lower region 18b is a reaction region 24, where foreign matter that has accumulated at the filter element on the raw gas side is removed from a corresponding one of the filter elements 14 (e.g., by applying a pressure pulse to the corresponding filter element 14, see Figure 2 The first closing device with the first cutting member 30 is arranged in the channel 28. The first cutting member 30 can be designed as a cut-off valve, a flap valve, a disc valve, or a pinch valve, just like the other cut-off members described herein.

[0092] In the example shown, the reaction zone 24 has a funnel-shaped container 32, which forms an agglomerate collection area 33. In the example shown, the container 32 has a side wall that tapers downward away from the raw gas space 15. The container 32 can also take another shape, such as a cylindrical shape or a rectangular shape. The container 32 has an optional additional fluid inlet 3 and an additional fluid outlet 40 at its top end 34 (that is, the end of the container 32 facing the raw gas space 15), and excess fluid (such as excess oxidant, excess cleaning fluid, heat transfer fluid for removing heat generated during the reaction process, or a mixture of the above fluids) can leave the container 32 through the additional fluid outlet 40. It should be noted that, if necessary, multiple additional fluid inlets 38 and multiple additional fluid outlets 40 can be provided, and the arrangement of these additional inlets or additional outlets on the container 32 can be selected as needed.

[0093] The container 32 has an oxidant inlet 36 in its lower region or at its bottom end 42 (i.e., at the end of the container 32 away from the raw gas space 15). The oxidant inlet 36 is configured to allow the oxidant stream to be introduced into the agglomerate collection area 33. In addition to oxidants such as oxygen, other fluids (e.g., inert fluids, especially inert gases such as nitrogen) can also be introduced into the container 32 around the agglomerate collection area 33 through the oxidant inlet 36. A mixture of additional fluids and oxidants can be used to adjust the appropriate concentration of the oxidant for cleaning purposes and / or for removing heat. If an additional fluid is used as a heat transfer fluid and / or a cleaning fluid, the additional fluid can be alternatively or additionally introduced into the container 32 via one or more additional fluid inlets (such as the above-mentioned additional fluid inlet 38). In particular, the oxidant inlet 36 can be configured as a fluidizing device such as a fluidizing disk, so that when the oxidant stream is introduced, the loosening or fluidization of the solid-containing material in the agglomerate collection area 33 can also be achieved.

[0094] The container 32 further comprises an outlet 39 for discharging solid-containing matter, which in the illustrated embodiment is located in the lower region of the container 32. Preferably, such solid-containing matter will include foreign matter containing oxides formed during the oxidation process. However, it is not necessary that all foreign matter and / or matter that has entered the agglomerate collection area 33, which has been cleared from the filter surface, has been completely oxidized when removed from the container 32 via the outlet 39. It is also possible that oxidation of oxidizable foreign matter can still occur downstream of the outlet 39.

[0095] The process environment in additive manufacturing processes that produce oxidizable or combustible residues should generally be inert and not change or at least not change excessively. This also applies to the treatment of the exhaust gases generated in the process, in particular if clean exhaust gases are recirculated to the process in a loop or circuit. If combustible foreign matter in the exhaust gas can be removed by a dry filter, an inert mixture of inert carrier gas and particulate foreign matter will generally enter the raw gas space, where the proportion of oxygen and other substances that can act as oxidants is below a predetermined threshold. Therefore, the filtration of the raw gas loaded with combustible foreign matter is carried out under inert conditions, and it is undesirable to add oxygen or other substances with an oxidizing effect to the raw gas space. This complicates the possibility of rendering harmless the solid-containing substances accumulated on the filter surface by oxidation.

[0096] exist Figure 1 The raw gas flow, which is schematically indicated by arrows 44 and carries foreign matter to be separated by the filter device 10, enters the raw gas space 15 surrounded by the housing 18 through the raw gas inlet opening 16 via the raw gas supply line 54. After entering the raw gas space 15, the raw gas flow 44 is conveyed to the filter unit 12. On the side of the housing 18 opposite to the raw gas inlet opening 16, there is a filter aid supply opening 20, through which a filter aid (for example, a solid with flame retardant properties such as CaCO3 or based on SiO2) can be supplied from a storage container to the raw gas space 15. The filter aid can be introduced into the raw gas space 15 before the raw gas flow 44 is filled into the raw gas space 15. The introduced filter aid is then accumulated in particular on the filter surface of the filter element 14 and / or on the wall of the raw gas space 15, wherein the filter aids each form a filter aid layer (pre-coating layer). The filter aid flow entering the raw gas space 15 through the filter aid supply opening 20 is passed through Figure 1 Indicated by arrow 45 in FIG.

[0097] Alternatively or additionally, the filter aid supply opening 52 can be arranged in the raw gas supply line 54. The raw gas supply line 54 is connected to the raw gas inflow opening 16. This allows the introduction of filter aid into the raw gas flow 44 before the raw gas flow 44 enters the raw gas space 15 of the filter device 10. This results in a favorable mixing of foreign matter contained in the raw gas flow 44 with the filter aid, so as to increase the autoignition threshold of the raw gas. Optionally, a baffle or distributor plate 56 can be arranged near the filter aid supply opening 52, so that the filter aid is evenly distributed in the raw gas flow 44.

[0098] exist Figure 2Schematically shown in FIG. 1 , a pressurized gas removal unit 58 is coupled to the filter unit 12, and the pressurized gas removal unit 58 is located in the clean gas space 17 of the filter unit 12 above the filter element 14. At certain time intervals, the pressurized gas removal unit 58 pressurizes the corresponding filter element 14, so that the filter element 14 is subjected to a pressure shock from the clean gas space 17. The pressure shock causes foreign matter such as easily self-igniting foreign matter, and in some cases also filtering aids, to accumulate on the filter surface on the raw gas side of the corresponding filter element 14 to fall off from the filter element 14 and fall downward due to their gravity. The substances removed from the filter surface then fall into the agglomerate collection area 33 in the reaction area 24 through the channel 28 together with the foreign matter and the filtering aids.

[0099] The first shut-off member 30 is normally open so that there is fluid communication between the raw gas space 15 and the reaction zone 24. This is maintained in particular at the beginning and during the cleaning cycle of the filter element 14. In this way, the material falling from the filter surface during cleaning can fall into the agglomerate collection area 33 of the reaction zone 24 unhindered or at least substantially unhindered and will not be significantly deposited on the bottom plate or wall of the housing 18 surrounding the raw gas space 15. Once the cleaning has been completed and the oxidation cycle has started in the reaction zone 24, the first shut-off member 30 is closed so that the agglomerate collection area 33 of the reaction zone 24 is separated from the raw gas space 15 in a fluid-tight manner for at least a period of time, during which an environment containing an oxidant is dominant in the agglomerate collection area 33. Then, the oxidant is introduced into the agglomerate collection area 33 via the oxidant inlet 36 to cause spontaneous oxidation of the material entering the agglomerate collection area 33. The oxidant inlet 36 is designed so that the oxidant flows through or mixes with the solid-containing material in the agglomerate collection area 33 (particularly the oxidizable material removed from the filter surface) and thus spontaneously initiates oxidation of such material, i.e., without the need for additional energy input through heating means, ignition means, etc. The oxygenated substances (now inert foreign matter) formed by oxidation, excess oxidant and other substances can then be transported via the outlet 39 along the discharge line 60 to the discharge area 62 downstream of the agglomerate collection area 33. After this discharge process is completed, the concentration of oxidant in the agglomerate collection area 33 has dropped to a level where contamination of the raw gas space 15 is no longer a concern, and the shut-off member 30 can then be opened again. In order to assist in the discharge of oxidant from the container 32 surrounding the agglomerate collection area 33, a scavenging fluid in the form of nitrogen, a rare gas or another inert gas can be introduced into the container 32 via an optional additional fluid inlet 38. This allows residual oxidant still present in the container 32 to be removed from the container 32 via the further fluid outlet 40 and thus from the agglomerate collection area 33 to create an inert environment in the container 32 or in the agglomerate collection area 33. When the shut-off member 30 is open, foreign matter from the raw gas flow 44 and material removed from the filter surface can enter the reaction area 24 again without intermediate storage. By not collecting foreign matter in the lower region 18b of the housing 18, dust bridges are effectively avoided, which would otherwise strongly impair the subsequent sliding of foreign matter into the reaction area 24.

[0100] As a variant, it is conceivable that a continuous flow of an inert fluid, for example nitrogen or a noble gas, passes at least temporarily through the container 32 via the oxidant inlet 36 and / or via the further fluid inlet 38, which continuous flow passes through the agglomerate collection area 33 of the reaction zone 24, flows to the outlet 39 and leaves the container 32 again via the outlet 39. Once the cleaning of the filter element 14 or filter elements has taken place and the shut-off member 30 is closed, a sufficient amount of oxidant can be added to the fluid flow so that the substances located in the agglomerate collection area 33 can react or transform by oxidation. Once the transformation has taken place to the desired extent, the supply of oxidant to the fluid flow can be stopped, and the foreign matter containing the oxide or the re-reacted foreign matter can be conveyed with the fluid flow from the agglomerate collection area 33 or from the container 32 via the discharge line 60 to the discharge area 62.

[0101] The coordination between the activation of the pressurized gas removal unit 58, i.e., the removal of the substances adhering to the filter surface by one or more corresponding filter elements 14, and the opening and closing of the cut-off member 30 is performed by the control unit 59. The control unit 59 can be configured so that the cut-off member 30 is open as a default setting, thereby causing foreign matter in the raw gas that has not reached the filter element 14 or has fallen off the filter element surface outside the removal cycle to fall directly into the agglomerate collection area 33 of the reaction area 24. Even during the removal of the filter element 14, the cut-off member 30 remains open to allow the substances removed from the filter surface to be discharged into the reaction area 24 without intermediate storage. As soon as the removal is completed, the control unit 59 closes the cut-off member 30 for a short time, so that the oxidant can be allowed to enter the reaction area 24, in particular, into the container 32 surrounding the agglomerate collection area 33, which is now separated from the raw gas space 15. After a predetermined time, it can be assumed that the substances removed from the filter surface in the agglomerate collection area 33 have been oxidized to a sufficient extent to form foreign matter containing oxides. To the extent that the oxidant added in the reaction is not consumed, the excess oxidant is then removed from the agglomerate collection area 33, so that an inert environment is again present in the reaction area 24, i.e., the oxidant concentration is so low that no oxidation occurs even if foreign matter or substances removed from the filter surface enter the agglomerate collection area 33. The control unit 59 can then reopen the cut-off member 30 to allow foreign matter and substances removed from the filter surface to enter the agglomerate collection area 33 again.

[0102] In certain embodiments, the container 32 may be arranged to be movable or acted upon by a stirring device and / or a knocking device to generate a corresponding rocking movement, vibration, shaking movement, etc. of the container 32 to facilitate subsequent or continued sliding of the solids-containing material downward through the outlet 39. In this way, as complete an emptying of the agglomerate collection area 33 as possible can be achieved.

[0103] In addition to the discharge line 60, the discharge area 62 preferably also includes a collecting container 64 in which foreign matter containing oxides is collected. Fluid matter, in particular gaseous matter, reaching the collecting container 64 via the discharge line 60 is discharged from the collecting container 64 again via the exhaust gas outlet 130.

[0104] Optionally, a second closing device with a second shut-off member 66 can be arranged in the discharge line 60, for example, in the area near the collecting container 64. Therefore, the second closing device is also connected to the discharge area 62. The second closing device is designed to separate the upstream part of the discharge area 62, which still belongs to the reaction area 24 and the oxidation of the substances containing foreign matter still occurs, from the downstream part, where the oxidation no longer occurs. However, it is not necessary to set up a second closing device. It has been found that the desired oxidation reaction can occur completely in the discharge area 62, in particular in the discharge line 60, and in particular can be completed before the substances transported by the discharge line 60 reach the downstream end of the discharge line 60, at the downstream end of the discharge line 60, the discharge line 60, for example, leads to the collecting container 64.

[0105] The downstream end of the discharge line 60 leads to a collecting container 64. When reaching the collecting container 64, the solid-containing matter, in particular the foreign matter containing oxides formed during oxidation, falls into the collecting container 64 in the discharge area 62 and can thus be disposed of. At the top, the exhaust gas outlet area 120 (see Figure 6 ) to the collecting container 64. In the exhaust gas outlet region 120, there is an exhaust gas outlet 130, through which excess fluid substances, in particular oxidants, cleaning fluids, transport fluids, heat transfer fluids and other fluids, can be discharged from the discharge region 62. If necessary, the excess fluid substances (hereinafter also referred to as exhaust gas) can be discharged to the environment or the exhaust system via the shut-off valve 78. Alternatively, as Figure 2 As shown, all or part of the excess fluid material can be returned to the reaction zone 24, in particular to the oxidant inlet 36. In this case as well, a shut-off valve 78 can optionally be provided. Figure 2 Arrangement shown.

[0106] Figure 3 Another embodiment of a container 32 is shown. Only the embodiments related to the container 32 will be described in more detail below. Figure 1 and Figure 2 The container has 32 different features. Figure 3 For a description of the additional features in Figure 1 and Figure 2 In the description of the invention, the same or corresponding features are indicated by the same reference numerals. Figure 3 In the embodiment of the present invention, a pneumatic delivery device (configured as a solid injector 80 in this case) is provided to deliver a substance from a container 32. In this embodiment, a hollow nozzle 68 extends from the top end 34 of the container 32 into the interior of the container 32. The tip of the hollow nozzle 68 extends to a position near the root or bottom end 42 of the container 32. The hollow nozzle 68 includes one or more openings in an area adjacent to its tip, through which a substance can be discharged from the container 32, and the hollow nozzle 68 is connected to the delivery port 74 of the solid injector 80.

[0107] Alternatively or in addition to the solid injector, an aspirator may be provided to transport substances, particularly gaseous substances, from the container 32. Like the solid injector, the aspirator may be connected to the container 32 via a hollow nozzle 68 and may be particularly provided for extracting or sucking away oxidants and other gaseous fluids from the agglomerate collection area 33.

[0108] In addition to the transport port 74, the solid injector 80 also has a transport fluid inlet 70, which can be supplied with a transport fluid (e.g., air), and a material discharge port 76, which communicates with the transport fluid inlet 70 and the transport port 74. The transport port 74 connects the hollow nozzle 68 to a channel, which connects the transport fluid inlet 70 to the material discharge port 76. The transport fluid inlet 70 generally has a shape that tapers toward the material discharge port 76, so that when acted upon by the transport fluid, the transport fluid in the channel is accelerated, thereby generating a negative pressure in the hollow nozzle 68 and thus sucking the solid-containing material out of the container 32 through the hollow nozzle 68. The material discharge port 76 of the solid injector 80 is connected to the discharge line 60. When the transport fluid inlet 70 is acted upon, the transport fluid is transported from the transport fluid inlet 70 to the discharge line 60 via the material discharge port 76, thereby generating a negative pressure in the hollow nozzle 68. Due to the negative pressure, the solid-containing substances (especially foreign substances containing oxides formed during the reaction) present in the container 32 are sucked into the hollow nozzle 68 together with the gaseous substances (especially unconsumed oxidant) and transported to the substance discharge port 76 through the hollow nozzle 68. In the process, the sucked substances are mixed with the transport fluid and transported to the discharge line 60 of the discharge area 62 through the substance discharge port 76.

[0109] Depending on the transport fluid entering the transport fluid inlet 70, the suction strength of the solid injector 80 can be adjusted, thereby adjusting the respective amounts of the solid-containing material and the gaseous material transported from the container 32, or adjusting the mixing ratio between the material transported from the container 32 and the mixed transport fluid. Ultimately, this allows precise control of the oxidation reaction occurring in the container 32 and any oxidation reaction that may also occur downstream of the solid injector 80 in the discharge line 60.

[0110] The foreign matter containing oxides can also be sucked out of the container 32 in an alternative manner. For this purpose, a negative pressure can be generated in the discharge area 62 by, for example, a blower or a suction device, whereby the foreign matter containing oxides is sucked into the discharge line 60 of the discharge area 62 through the hollow nozzle 68. In addition to the foreign matter containing oxides, for example, excess oxidant and / or additional substances or fluids can also be sucked out of the container 32. Once the extraction is completed, that is, as long as little or no oxidant remains in the agglomerate collection area 33, the cutting member 30 can release the channel 28 from the raw gas space 15 to the agglomerate collection area 33. In such an arrangement, the transport fluid inlet 70 is not necessary, but can be optionally provided to help remove the impurities containing oxides.

[0111] Instead of or in addition to using negative pressure to extract foreign matter containing oxides, a transport fluid (particularly a transport gas) can also be introduced into the container 32 via the fluid inlet 38. The transport fluid is under positive pressure, and then pneumatically forces foreign matter containing oxides to enter the discharge line 60 through the hollow nozzle 68 to reach the discharge area 62 in the case of gas. In order to assist, the transport fluid can be introduced into the discharge line 60 through the transport fluid inlet 70 to further transport foreign matter containing oxides and prevent the formation of dust bridges. The transport fluid can be an inert fluid such as nitrogen. The transport fluid can also include an oxidant such as oxygen. In this way, it can be ensured that the oxidation reaction continues to occur when the material is transported from the container 32 to the discharge area 62. For example, if it is necessary to add an oxidant to the transport fluid, it is convenient to use air as the transport fluid. If necessary, an inert fluid can also be used as the transport fluid and the oxidant can be introduced into the container 32 through a separate inlet.

[0112] In order to safely remove excess oxidant from the agglomerate collection area 33 or the container 32 of the reaction area 24, the excess oxidant can be removed from the interior of the container 32 via the fluid outlet 40 after removing the foreign matter containing the oxide, preferably by allowing an inert fluid (such as nitrogen or an inert gas) to pass through the fluid inlet 38 or the oxidant inlet 36, and the inert fluid replaces the excess oxidant from the agglomerate collection area 33 or the container 32 of the reaction area 24.

[0113] In addition, it is also possible to supply an inert fluid (e.g., an inert gas such as nitrogen) to the container 32 through the solid injector 80 after the material has been removed from the container 32 through the solid injector 80. The solid injector 80 has an additional port 72 that can act with a purge fluid to restore a potentially blocked fluid connection between the hollow nozzle 68 and the material discharge port 76. By applying the inert fluid to the purge port 72, and if necessary, closing the material discharge port 76, the inert fluid can be easily introduced into the container 32 to flush or purge any oxidant still remaining in the agglomerate collection area 33.

[0114] Figure 4 Another embodiment of a container is shown, in which, similar to Figure 3 , a pneumatic delivery device (configured as a solid injector 80 in this case) is provided to deliver the substance from the container 32. Only the components different from the solid injector 80 will be described in more detail below. Figure 1 , Figure 2 and Figure 3 To describe the characteristics of the container 32. Figure 4 For other features in Figure 1 , Figure 2 and especially Figure 3 , wherein identical or corresponding features are provided with the same reference numerals.

[0115] and Figure 3 The embodiments are different, according to Figure 4 The embodiment has a solid injector 80 arranged at the lowest point of the container 32, in the variation shown, the side walls of the container 32 converge downwardly, wherein these side walls are closest to each other. An opening is formed at the bottom of the container 32, which is connected to the delivery port 74 of the solid injector 80, and the material can be sucked from the container 32 through the opening. It is understood that a plurality of such openings can also be formed at the bottom of the container 32. In this embodiment, the delivery fluid inlet 36 of the solid injector 80 (which can be acted upon by the delivery fluid (e.g., air)) also serves as the oxidant inlet 36 of the container 32 and is therefore indicated by the reference numeral 36.

[0116] The material discharge port 76 is further connected to the discharge line 60. Generally, the transport fluid inlet 36 is connected to the material discharge port 76 via a channel having a shape that tapers toward the material discharge port 76 so that the transport fluid in the channel is accelerated when the transport fluid is applied to the transport fluid inlet 36. When the transport fluid is applied to the transport fluid inlet 36, the transport fluid is introduced from the transport fluid inlet 36 to the discharge line 60 via the material discharge port 76, thereby generating a negative pressure, which causes the solid-containing material (particularly the foreign matter containing the oxide formed during the reaction) present in the container 32 to be sucked or drawn in together with the gaseous material (particularly the unconsumed oxidant) and transported to the material discharge port 76. In this process, the sucked material is mixed with the transport fluid and transported to the discharge line 60 of the discharge area 62 through the material discharge port 76.

[0117] When only a slight positive pressure is applied to the transport fluid inlet 36, the acceleration of the transport fluid in the passage to the material discharge port 76 is insufficient to generate a significant negative pressure. In this case, the transport fluid is introduced into the container through the transport port 74. This effect can be further enhanced by closing the material discharge port 76. Therefore, if the transport fluid inlet 36 of the solid injector 80 is subjected to a transport fluid (such as air) containing an oxidant under a slight positive pressure, the net effect is to supply the oxidant to the container 32 or the agglomerate collection area 33. In addition, Figure 4 The operation of the solid injector 80 is Figure 3 The operation of the solid injector 80 shown in FIG. 8 is the same.

[0118] Figure 4 The solid injector 80 shown in FIG. 1 also has a port 72 that can act with a purge fluid to restore a potentially blocked fluid connection between the delivery port 74 and the material discharge port 76. By applying an inert fluid to the purge port 72, and if necessary, closing the material discharge port 76, an inert fluid can be easily introduced into the container 32 to purge any oxidant still remaining in the agglomerate collection area 33. By applying an inert fluid containing an oxygenating agent to the port 72 in this manner, an oxidant can also be introduced into the agglomerate collection area 33 if necessary.

[0119] Figure 5 An agglomerate collection region 33 of the reaction zone 24 located in the vessel 32 is shown, wherein the first shut-off member 30 is upstream in the flow direction of the purged material. Figure 5It is schematically shown how the material 89 removed from the filter surface falls into the container 32 from the direction of the shut-off member 30. In doing so, the falling material removed from the filter surface crosses the oxidant flow 90 flowing from the oxidant inlet 92 to the oxidant outlet 94. As the oxidant flow 90 passes through, the material removed from the filter surface spontaneously reacts with the oxidant, thereby being converted into poorly reactive or inert and / or oxidant-containing foreign matter 91. The oxidant-containing foreign matter formed during oxidation is mainly discharged through the oxidant outlet 94 via the discharge line 60 ( Figure 5 The oxidant stream 90 is discharged to a discharge area 62 downstream of the vessel 32 (not shown). Oxidation of foreign matter that has not yet been oxidized may also continue in the discharge line 60. The heat generated by the reaction may be dissipated through the oxidant outlet 94 along with the oxidant stream 90, which is typically a mixture of an oxidant such as oxygen and an inert component such as nitrogen or an inert gas.

[0120] Figure 6 An embodiment of an exhaust gas outlet region 120 leading out of a collection container 64 is shown. The exhaust gas outlet region 120 comprises an additional filter unit 122 mounted on a partition 124. The additional filter unit 122 may comprise one or more filter elements. The partition 124 separates the exhaust gas outlet region 120 into a raw gas space 126 and a clean gas space 128. A mixture of solid-containing substances (particularly foreign matter containing oxides, unoxidized foreign matter, possible filter aids, other solids and agglomerates of such substances) and fluid-phase substances, particularly gaseous substances (particularly excess oxidant, transport fluid, cleaning fluid, cooling fluid, etc.) enters the raw gas space 126. The additional filter unit 122 is configured to filter the mixture arriving at the raw gas space 126 to remove particulate oxidation residues and other particulate foreign matter. The filtered mixture of the fluid phase is then present in the clean gas space 128 and is discharged through an exhaust gas outlet 130 located at the clean gas space 128. In particular, the mixture of fluid phases is gaseous and is therefore referred to in simplified form below as waste gas. This waste gas can be discharged into the environment, for example, via a shut-off device or into an external waste gas system. Alternatively, Figure 6 As shown, the exhaust gas can also be returned to the reaction zone 24, for example to the oxidant inlet 36. It is conceivable that a portion of the exhaust gas is discharged to the surrounding or external exhaust system and another portion of the exhaust gas is returned to the reaction zone 24, for example to the oxidant inlet 36. In this case, the ratio of the exhaust gas flow returned to the reaction zone 24 to the exhaust gas flow discharged can be controlled. In particular, the control can be arranged so that always only so much exhaust gas is returned to the circuit, in particular to the reaction zone 24, so that the fluid pressure (in particular the gas pressure) in the circuit system (in particular in the reaction zone 24) does not exceed a predetermined upper limit value, in particular remains within a predetermined range.

[0121] In addition, a pressurized gas removal unit connected to the additional filter unit 122 is arranged in the clean gas space 128, and the pressurized gas removal unit is designed to generate a pressure pulse acting on the filter element for cleaning. The pressure pulse reaches the clean gas space 128 via the pressurized gas opening 132 from the pressurized gas reservoir 134, and reaches the filter element of the additional filter unit 122 from the clean gas space 128. The pressurized gas reservoir 134 can preferably be filled with pressurized gas via a pressurized gas pipeline 136. Once the filter performance of the additional filter unit 122 deteriorates, the pressurized gas cleaning is used to clean the additional filter unit 122. In this case, the pressurized gas is introduced into the clean gas space 128 in the form of a pressurized gas pulse, whereby the filter element wall is subjected to the pressure pulse and foreign matter that has accumulated on the raw gas side of the additional filter unit 122 is removed from the additional filter unit 122. These foreign matter then falls into the collection container 64 from the exhaust gas outlet area 120 through the channel 138. A shut-off member 140 is optionally arranged in the channel 138 to separate the discharge region 62 from the exhaust gas outlet region 120. It should be noted that it is not necessary to equip the further filter unit 122 with a cleanable filter element and that, for example, a storage filter in the further filter unit 122 which has to be replaced from time to time can be used very well.

[0122] In order to achieve the recirculation of fluids, in particular the recirculation of transport fluids and / or unconsumed oxidants, it can be provided that the exhaust gas outlet 130 is connected to the reaction zone 24, in particular to the oxidant inlet 36, such as at Figure 2 Schematically shown as an exhaust gas recirculation line 150. It should be understood that Figure 2 and Figure 6 As shown, the shut-off valve 78 in the exhaust gas recirculation line 150 is optional, and an exhaust gas recirculation line 150 without a shut-off valve is also possible. This recirculation creates a closed loop, whereby the inert fluid added to the aforementioned dry filtration process as a transport fluid and / or a cleaning fluid and / or a heat dissipation fluid can be recirculated in the process via the exhaust gas recirculation line 150 after passing through the process. In this way, a substantial saving of the required inert fluid can be achieved.

[0123] Since the oxidant, in particular oxygen, is consumed during the process of the oxidation treatment of the filter residue described, it is meaningful to add the oxidant again to the fluid returning from the exhaust gas outlet 130 to the reaction zone 24, in particular to the oxidant inlet 36, to the extent that the oxidant is consumed during the process. To this end, a sensor 142 can be arranged in the exhaust gas recirculation line 150, for example between the exhaust gas outlet 130 and the oxidant inlet 36, to determine the loss of oxidant in the fluid flow leaving the exhaust gas outlet 130 relative to the desired concentration of oxidant in the oxidant flow entering the container 32 at the oxidant inlet 36. In addition, a device 144 can be provided for supplying oxidant to the recirculating fluid flow as a function of the loss of oxidant determined by the sensor 142.

[0124] exist Figure 2 In the example shown, the sensor 142 is located at the oxidant inlet 36 and detects the actual concentration of the oxidant in the oxidant stream as it enters the vessel 32 or the agglomerate collection area 33 of the reaction zone 24. The means 144 for supplying the oxidant to the recirculating fluid stream opens into the exhaust gas recirculation line 150 at a position upstream of the sensor 142 and is controlled so that the oxidant concentration sensed at the sensor 142 is maintained at a predetermined value or within a predetermined range around the predetermined value.

[0125] For example, the amount of fluid carried in the process can be kept constant by monitoring the fluid pressure in the recirculating fluid stream. For example, this can be achieved by sensing and controlling or adjusting the pressure at the exhaust gas outlet 130, at the oxidant inlet 36, or in the exhaust gas recirculation line 150. Figure 2 As shown, for this purpose, for example, a pressure reducing valve 146 can be arranged in the exhaust gas recirculation line 150. By means of the pressure reducing valve, a predetermined pressure can be set in the exhaust gas recirculation line 150, and thus the mass flow of the fluid phase in the loop (i.e., the sum of the oxidant and other fluids such as feed fluid, purge fluid, heat transfer fluid) can ultimately be kept constant.

[0126] By means of an arrangement of the type described, the mass flow of the fluid carried in the circuit and the concentration of the oxidant in the circuit can be controlled or regulated in a simple manner. Thus, the intensity of the oxidation reaction taking place during the treatment of the filter residue can be very well controlled or regulated in a closed control loop in such a way that a sufficiently effective oxidation of the combustible substances is achieved without generating too much reaction heat.

Claims

1. A method for dry filtering a gas stream carrying foreign matter, the method comprising: A raw gas flow (44) containing foreign matter is introduced into a raw gas space (15) of a filter unit (12), wherein the filter unit (12) has at least one filter surface which separates a raw gas side from a clean gas side, supplying an oxidant to a reaction zone (24) located on the feed gas side of the filter surface downstream of the filter surface; causing foreign matter contained in the material removed from the filter surface and / or contained in the feed gas stream to react with the oxidant in the reaction zone (24) to form foreign matter containing an oxide; wherein the reaction zone is downstream of the raw gas space with respect to the transport of foreign matter which has accumulated on the filter surface and has been removed from the filter surface during a removal cycle, It is characterized in that foreign matter containing oxides formed during the reaction and, if applicable, also foreign matter which has not yet reacted are discharged by means of a pneumatic conveying device (80).

2. The method according to claim 1, wherein: The pneumatic conveying device (80) is a conveying device that operates as a solid injector or a jet pump.

3. The method according to claim 1, wherein: Oxidant that is not consumed during the reaction of material removed from the filter surface with the oxidant is removed from the reaction zone (24).

4. The method according to claim 1 or 2, in, An oxidant is supplied to the reaction zone (24) via an oxidant inlet (36) and removed via an oxidant outlet (39).

5. The method according to claim 4, in, The oxidant outlet (39) is different from the oxidant inlet (36).

6. The method according to claim 4, in, Unconsumed oxidant together with the foreign matter containing oxides formed during the reaction and, if applicable, also foreign matter which has not yet reacted, are discharged via the same oxidant outlet (39).

7. The method according to claim 6, in, The reaction zone (24) includes a region downstream of the oxidant outlet (39).

8. The method according to claim 4, in, The oxidant outlet (39) is connected to the pneumatic conveying device (80).

9. The method according to claim 1, in, The reaction area (24) has a negative pressure applied to the reaction area (24).

10. The method according to claim 9, in, During and / or after the reaction of the material removed from the filter surface with the oxidant, a negative pressure is applied to the reaction zone (24).

11. The method according to claim 1, in, During the reaction of the material removed from the filter surface with the oxidant, the unconsumed oxidant is drawn from the reaction zone (24) by the pneumatic conveying means.

12. The method according to claim 1, in, The reaction zone (24) is exposed to an inert fluid.

13. The method according to claim 12, in, The reaction of the substances removed from the filter surface with the oxidant takes place in a reaction stage, and after the respective reaction stage, the reaction zone is subjected to an inert fluid without the addition of the oxidant.

14. The method according to claim 12, in, An inert fluid is supplied to the reaction zone via a further fluid inlet (38) different from the oxidant inlet (36).

15. The method according to claim 4, in, The inert fluid and / or the oxidant are discharged from the reaction zone through a further outlet (40) provided in addition to the oxidant outlet (39).

16. The method according to claim 1, in, The reaction zone (24) has a heat transfer fluid flowing through the reaction zone (24) for removing heat generated during the reaction of material removed from the filter surface with the oxidant.

17. The method according to claim 1, in, The reaction area (24) includes an agglomerate collection area (33), which is configured to receive substances removed from the filter surface, wherein foreign matter or agglomerates containing foreign matter that have accumulated on the filter surface are removed and collected and stored in the agglomerate collection area (33).

18. The method according to claim 17, in, The material removed from the filter surface is transported from the agglomerate collection area (33) to a downstream discharge area (62), wherein the discharge area (62) includes at least a portion of the reaction area (24); and an oxidant is supplied to the agglomerate collection area (33) and / or the discharge area (62).

19. The method according to claim 18, in, A first closing device having a first cutting member (30) is connected to the agglomerate collection area (33), and the closing device is designed so that the material that has fallen off from the filter surface during the cleaning process can be collected in the agglomerate collection area (33), and after the cleaned material is collected in the agglomerate collection area (33), the reaction area (24) is closed relative to the raw gas space (15), at least until the oxidant concentration in the reaction area (24) and / or the agglomerate collection area (33) has dropped to a sufficient extent.

20. The method according to claim 19, in, The discharge area (62) comprises a second enclosure (66), wherein the reaction area (24) is located between the first enclosure and the second enclosure; and / or wherein the discharge area (62) comprises a collection container (64) for solid-containing material.

21. The method according to claim 1, in, After leaving the reaction zone (24), the unconsumed oxidant in the reaction zone (24) and, if applicable, also the further fluid accumulated as excess fluid are fully or partly recirculated to the reaction zone (24).

22. The method according to claim 21, in, A control / regulation unit is provided, which is arranged so that the fluid pressure in the reaction area (24) does not exceed a predetermined upper limit value or remains within a predetermined pressure range.

23. A filter device (10) for cleaning raw gas carrying foreign matter, comprising: at least one filter element (14) having at least one filter surface which separates a raw gas side from a clean gas side in a raw gas space, to which a raw gas flow (44) containing foreign matter can be supplied; an oxidant supply adapted to supply oxidant to a reaction zone (24) on the feed gas side of the filter surface downstream of the filter surface; causing foreign matter contained in the material removed from the filter surface and / or in the feed gas stream (44) to react with an oxidant in the reaction zone (24) to form foreign matter containing an oxide; wherein the reaction zone is downstream of the raw gas space with respect to the transport of foreign matter which has accumulated on the filter surface and has been removed from the filter surface during a removal cycle, It is characterized in that foreign matter containing oxides formed during the reaction and, if applicable, also foreign matter which has not yet reacted are discharged by means of a pneumatic conveying device (80).

24. The filter device (10) according to claim 23, wherein The pneumatic conveying device (80) is configured to operate as a solid injector or jet pump.

25. The filter device (10) according to claim 23, in, During the reaction of the material removed from the filter surface with the oxidant, unconsumed oxidant can be removed from the reaction zone (24).

26. The filter device (10) according to claim 23, comprising an oxidant inlet (36) arranged to supply the oxidant to the reaction zone (24) and an oxidant outlet (39), wherein the oxidant inlet (36) is arranged to supply the oxidant to the reaction zone (24), and the oxidant outlet (39) is arranged to remove the oxidant from the reaction zone (24), wherein: The oxidant outlet (39) is different from the oxidant inlet (36).

27. The filter device (10) according to claim 26, The filter device (10) is designed to discharge unconsumed oxidant together with the foreign matter containing oxides formed during the reaction and, if applicable, also foreign matter which has not yet reacted, through the same oxidant outlet (39).

28. The filter device (10) according to claim 26, in, The reaction zone (24) includes a region downstream of the oxidant outlet (39).

29. The filter device (10) according to claim 26, in, The oxidant outlet (39) is connected to the pneumatic conveying device (80).

30. The filter device (10) according to claim 23, The filter device (10) is arranged to apply negative pressure to the reaction zone (24) during and / or after reaction of material removed from the filter surface with an oxidant.

31. The filter device (10) according to claim 23, The filter device (10) is arranged to act on the reaction zone (24) with an inert fluid.

32. The filter device (10) according to claim 31, comprising a control unit (59) arranged such that a reaction of the substances removed from the filter surface with the oxidant occurs in a reaction phase, wherein After the respective reaction phase, an inert fluid without added oxidant is applied to the reaction zone (24).

33. The filter device (10) according to claim 32, Further comprising an additional fluid inlet (38) leading into the reaction zone (24), the additional fluid inlet (38) being different from the oxidant inlet (36) for introducing an inert fluid and / or a heat transfer fluid.

34. The filter device (10) according to claim 26, Further comprising an additional outlet (40) for discharging an inert fluid and / or an oxidant, the additional outlet (40) being provided in addition to the oxidant outlet (39).

35. The filter device (10) according to claim 23, in, The reaction area (24) includes an agglomerate collection area (33), which is arranged to receive material removed from the filter surface, wherein foreign matter or agglomerates containing foreign matter that have accumulated on the filter surface can be collected and stored in the agglomerate collection area (33) after they have been removed.

36. The filter device (10) according to claim 35, Further comprising a discharge area (62) located downstream of the agglomerate collection area (33) and into which material removed from the filter surface can be transported, wherein The discharge region (62) includes at least a portion of the reaction region (24), and An oxidizing agent can be supplied to the agglomerate collection area (33) and / or the discharge area (62).

37. The filter device (10) according to claim 36, in, The agglomerate collection area (33) has a first closing device connected to it, the first closing device has a first cutting member (30), and the first closing device is designed so that the first closing device enables the material that falls off from the filter surface during the cleaning process to be collected in the agglomerate collection area (33), and after the cleaned material is collected in the agglomerate collection area (33), the reaction area (24) is closed relative to the raw gas space (15), at least until the oxidant concentration in the reaction area (24) has dropped to a sufficient extent.

38. The filter device (10) according to claim 37, in, The discharge region (62) includes a second enclosure, wherein the reaction region (24) is located between the first enclosure and the second enclosure.

39. The filter device (10) according to claim 38, in, The discharge area (62) comprises a collecting container (64) for separating solid-containing matter, wherein the collecting container (64) has an outlet for the fluid matter, wherein a further filter unit (122) for removing foreign matter from the fluid matter is connected to the outlet.

40. The filter device (10) according to claim 23, further comprising a fluid recirculation unit (150) arranged such that, after leaving the reaction zone (24), the oxidant not consumed in the reaction zone (24) and, if applicable, also further fluid accumulated as excess fluid, is fully or partially recirculated into the reaction zone (24), wherein A control / regulation unit is provided, which is arranged so that the fluid pressure in the reaction zone (24) does not exceed a predetermined value or remains within a predetermined range.

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