METHOD FOR CLEANING A FILTER

Description

field of technology

[0001] The invention relates to a method for cleaning a filter in a filter device comprising a filter housing and the filter located therein, wherein the filter device has a filter material collection chamber for receiving filter material that accumulates during the cleaning of the filter. State of the art

[0002] In metal printing equipment, such as laser sintering or laser melting systems, and also, for example, so-called 3D laser printing systems, it is known to supply process gas to the cabin of the printing equipment in a recirculating process, which is cleaned or regenerated in a filter device with regard to impurities (e.g., soot) that arise during the metal printing process, especially due to the high heat exposure, and which can arise particularly from the laser application.

[0003] The production of a die-casting part in the metal pressure device preferably takes place in a protective gas atmosphere created by the process gas. Typically, an inert gas such as argon or nitrogen is used as the process gas, or alternatively, argon or nitrogen alone. However, a mixture of gases, particularly inert gases, can also be used as the process or protective gas. Generally, the aim is for the atmosphere, especially within the chamber, to contain no or practically no oxygen. Therefore, in the case of the metal pressure device, the medium flowing through the filter system is the process gas.

[0004] Depending on the size and / or complexity of the printed item to be produced, such a printing process can easily extend over several hours or even several days.

[0005] A metal pressure device is known, for example, from DE 10 2017 206 792 A1. In connection with a filter device, such a metal pressure device is known, for example, from DE 20 2012 013 036 U1. A method for cleaning a filter is known from DE 10 2015 118 746 A1. Furthermore, a filter device of the type in question and a method for cleaning the filter are described in DE 10 2019 132 349 A1.

[0006] The filter material collected during filter cleaning typically consists of a highly reactive material. Consequently, there is an increased risk of ignition when this filter material leaves the protective atmosphere created by the process gas during disposal.

[0007] In this context, it is known, particularly in smaller systems, to use disposable filters that are discarded once a predetermined fill level is reached. It is also known to flood disposable filters, especially those with a larger capacity, with water and / or oil, thereby passivating the filter material. After this, the disposable filter can be removed from the housing and disposed of. The housing is then cleaned and fitted with a new disposable filter.

[0008] Solutions are also known in which a fire retardant, such as lime or glass granules, is continuously blown into the filter housing, ensuring that the entire filter surface is wetted and mixes with the filtered material. During the cleaning process, this filter material-fire retardant mixture is transferred to a collection chamber. Each cleaning cycle of the filter produces a relatively large amount of waste, necessitating relatively frequent emptying of the collection chamber.

[0009] Cleaning the filter by spraying it with oil is problematic with regard to disposal.

[0010] From DE 10 2006 012 933 A1, a method for cleaning a filter in a filtering device is known, in which the filter material collection chamber is first flooded with an inert gas. From DE 10 350 395 A1, a method for cleaning a filter in a filtering device is known, in which the filter material collection chamber is filled with additive particles. After reaching a predetermined fill level, the filter material collection chamber is replaced with a new one.

[0011] From CN 109248508 A a method for cleaning a filter in a filter device is known, in which a pre-introduced inert material, which may be calcium carbonate powder, is contained in the filter material collection chamber. Summary of the invention

[0012] Starting from the aforementioned prior art, the invention addresses the problem of providing an advantageous method for cleaning a filter in a filter device.

[0013] This problem is solved in the subject matter of claim 1, wherein the focus is on the fact that, in the course of removing the filter material collection chamber from the filter device, a targeted exchange of a chamber atmosphere against the surrounding atmosphere is carried out, wherein, in conjunction with an inflow of atmospheric air, a mixing movement of the filter material collection chamber is carried out to mix the filter material with the solid material.

[0014] The fire retardant, which according to the invention is already incorporated into the filter material collection chamber before a first cleaning process of the filter, is preferably a prerequisite for a controlled passivation of the filter material to be carried out in a later process step. The fire retardant is incorporated into the collection chamber, which receives the cleaned filter material, before a first cleaning process. This quantity of fire retardant is sufficient for the entire number of cleaning processes for which the collection chamber is designed.

[0015] During the controlled reaction facilitated by the fire retardant, a temperature increase may occur within the collection chamber. However, this increase is so small that the heat can be dissipated to the surroundings via the chamber's housing wall.

[0016] The filter material collection chamber can be closed with a lid that allows for targeted air exchange with the surrounding atmosphere.

[0017] The air exchange takes place with the collection chamber removed from the filter device and preferably after an initial mixing of the chamber contents.

[0018] By enabling a controlled exchange of air with the surrounding atmosphere, a process can be carried out to passivate the initially reactive filter material collected in the collection chamber. This air exchange allows for targeted oxidation with atmospheric oxygen within the collection chamber. The controlled air exchange can be achieved, for example, by actuating a valve located in the lid. Alternatively, such a valve can also be located outside the lid, for example, connected via a flow line that forms a closed connection between the valve and an opening in the lid that is connected to the interior of the collection chamber.

[0019] The filter material collection chamber can be rotatable and / or swiveling in a receiving device.

[0020] By rotating and / or pivoting the collection chamber, which is preferably located away from the filter device and housed in the receiving device, a thorough mixing of the filter material contained in the collection chamber can be advantageously achieved, for example, to support a passivation or oxidation process. The entire collection container is preferably rotated and / or pivoted.

[0021] The rotation and / or pivoting, or preferably the rotation in a pivoted position of the collecting chamber, can initially be performed about a body axis corresponding, for example, to a rotation axis of the collecting chamber, and preferably also about a transverse axis to this body axis. Rotation or pivoting about any other geometric axes, preferably intersecting the body axis and / or the transverse axis, is also possible.

[0022] When the collection chamber rotates or pivots around several geometric axes simultaneously, wobbling of the chamber can occur within the receiving device. Furthermore, jerky rotational and / or pivoting movements, or wobbling movements, can also occur, for example, to detach a filter cake that may have settled on the inner wall of the collection chamber.

[0023] In connection with the proposed method, the filter material collection chamber can preferably be filled with a gas prior to a first filter cleaning process to prevent fire. A gas that prevents the potential fire hazard of the collected filter material in the collection chamber is preferred. Such a gas, in particular, prevents uncontrolled oxidation of the reactive filter material. Furthermore, it is preferably desired that the atmosphere in the collection chamber contains no or practically no oxygen.

[0024] In a preferred method, the filter material collection chamber is filled with a protective gas to prevent fire. Preferably, this protective gas corresponds to the process gas used, from which the reactive filter material is filtered out.

[0025] The protective gas is preferably an inert gas, such as argon or nitrogen, and argon or nitrogen can preferably be used as the sole gas. However, a mixture of gases, particularly inert ones, can also be used as the protective gas.

[0026] The filter media collection chamber is partially filled with a solid material. This solid material, which acts as a fire-retardant, is already filled with the filter media collection chamber before the first cleaning process. During cleaning, any reactive filter media detached from the filter is deposited onto this base fill. The solid material is not blown into the filter housing and onto the filter surface during each cleaning process, as is known from prior art, but rather a predetermined quantity is pre-filled into the collection chamber before the first cleaning process. During filter cleaning, preferably only the filter media detached from the filter is transferred to the collection chamber and subsequently mixed with the solid material and neutralized in a downstream process.

[0027] In the known method of injecting a fire retardant into the collection chamber, the filter material remains reactive during and after discharge into the environment. Accordingly, it must continue to be securely enclosed with large quantities of fire retardant even after discharge. In contrast, the proposed method advantageously requires significantly less fire retardant compared to solutions involving injection into the filter chamber. The filter material is only discharged after complete passivation.

[0028] The solid material is preferably filled into the collection chamber to approximately 25 to approximately 75% of its usable capacity, depending on the reactivity of the filter material, before its first use.

[0029] For example, during a cleaning cycle, a filter media volume of approximately 15 to 25 cm³ can be generated after about 10 to 14 operating hours, preferably about 20 cm³ after 12 operating hours. Assuming a maximum permissible filling of the filter media collection chamber with approximately 3,000 cm³ of filter media, this results in approximately 120 to 200 permissible filter cleaning cycles, or 1,500 to 2,000 operating hours as the replacement or emptying interval for the collection chamber. In filter systems with, for example, two parallel filter units, the time between cleaning cycles doubles, so that, with, for example, 120 to 200 permissible cleaning cycles per filter unit, a total operating time of 3,000 to 4,000 hours is achieved, meaning that each container only needs to be removed and emptied after 3,000 to 4,000 hours.With 7-day operation of the entire system and 90% availability, it is advantageous that a collection chamber only needs to be emptied every 6 months.

[0030] The solid material can be granular. With respect to a cross-sectional area through such a granular solid material, a maximum preferred dimension (grain size) of the solid is obtained, which is preferably less than 1 mm, and more specifically less than 0.5 mm, down to, for example, 0.5 mm.

[0031] Furthermore, according to a preferred method, a glass-like solid material can be used. For example, this could be glass granules, for instance with a grain size of approximately 0.1 to approximately 0.3 mm.

[0032] Preferably, once a predetermined fill level of filter material has been reached in the filter material collection chamber, the filter device can be removed and the protective gas replaced with atmospheric gas.

[0033] To further prepare such reactive filter material for final disposal, the filter material collection chamber is removed from the filter unit. The filter unit can then be fitted with another collection chamber, preferably refilled with fire retardant, so that the filter unit can be reintegrated into the usual purification process for the process gas.

[0034] During the removal of the filter device, preferably after completion of the removal process, the chamber atmosphere (protective gas) is selectively replaced with the surrounding atmosphere. Preferably, the protective gas is successively replaced with ambient air, whereby the atmospheric oxygen entering the collection chamber gradually oxidizes and thus passivates the filter material. This targeted and preferably delayed exposure of the filter material to oxygen essentially eliminates the risk of fire.

[0035] The filter media collection chamber can have a usable storage volume for filter media of, for example, approximately 10,000 to 25,000 cm³ or more, or, for example, approximately 20,000 cm³. The total volume, on the other hand, can be chosen to be approximately 20 to 25% larger.

[0036] In terms of the recording volume, the exchange can take place over a period of several hours, for example about 2 hours or more, up to, for example, 12 hours or more.

[0037] In an advantageous further development of the method, it is provided that, in conjunction with the inflow of atmospheric air, the filter material collection chamber is moved to mix the filter material, preferably the filter material itself, with the solid material. Such mixing of the filter material can initially take place alone, without the inflow of atmospheric air, in order to achieve a uniform mixture of the filter material and the preferably intended solid material. Subsequently, a negative pressure can optionally be created in the filter material collection chamber by extracting the protective gas. Then, by mechanical means, for example a throttle valve, preferably while continuing the mixing process, the interior of the collection chamber can be connected to the surrounding atmosphere to allow for a targeted or controlled reaction of the filter material with atmospheric oxygen.

[0038] In particular, due to intensive mixing with the solid material, only a comparatively small amount of filter material can react at any given time on the surface of the filter material / solid material mixture with the atmospheric oxygen flowing very slowly and in a controlled manner into the collection chamber.

[0039] Through targeted reaction with atmospheric oxygen, the filter material is passivated to such an extent that any risk during the final disposal of the filter material is eliminated.

[0040] For rotating and / or swiveling movement, and if necessary also for targeted air exchange with the surrounding atmosphere, a separate receiving device for a filter material collection chamber of the type described above can be used, for example.

[0041] The filter material collection chamber removed from the filter unit can be connected to a transport container, particularly after passivation of the filter material, preferably by mixing with solid material and reacting with atmospheric oxygen. Preferably, the filter material is transferred directly into a compartment of the transport container that is sealed off from the surrounding atmosphere. After passivation, the filter material collection chamber is emptied into the transport container, optionally using a receiving device. This emptying can, preferably, be solely gravity-driven, with the filter material collection chamber being moved, for example, into an upside-down position and connected to the transport container in this position.The transfer of filter material from the collection chamber to the transport container preferably takes place in an area sealed off from the surrounding environment. This prevents contamination of the environment by escaping filter material.

[0042] Along with the filter material, the fire retardant, for example in the form of a solid material, which was filled into the collection chamber before the first intake of filter material, is also disposed of during the emptying into the transport container.

[0043] Before the filter material collection chamber is reattached to the filter unit, it is refilled with a fire retardant. This refilling can be carried out with solid material and / or protective gas. Alternatively, it can be filled with a fire retardant immediately after the filter material collection chamber has been attached to the filter unit.

[0044] In a preferred embodiment, the filter material collection chamber has a self-closing valve. This valve closes the opening that allows the passage of separated filter material into the collection chamber during normal filter operation, particularly when the collection chamber is removed from the filter unit. A further preferred feature is a device that can actuate the valve for gas exchange with atmospheric gas when the filter material collection chamber is removed from the filter unit. This device can be formed entirely or partially by the lid or a fixture integrated into the lid.

[0045] Furthermore, the device may, for example, include a device for moving the chamber-side valve into the open position and, if necessary, a separate valve design, for example in the form of a throttle valve, for the targeted and controlled intake of air atmosphere into the collecting chamber.

[0046] The collection chamber may also be equipped with rod-like handling elements. These handling elements can be used to transport the collection chamber after it has been removed from the filter unit, for example, by hand or by means of a trolley. Furthermore, the rod-like handling elements, in particular parts or sections thereof, may be designed to directly or indirectly act upon a releaseable locking mechanism that secures the collection chamber to the filter unit. Brief description of the drawings

[0047] The invention is explained in more detail below with reference to the accompanying drawing, which merely represents an exemplary embodiment. It shows: Fig. 1 in a schematic perspective view of a metal pressure device with an associated filter module, comprising several filter devices; Fig. 2 in a perspective view of the arrangement of three filter devices connected in parallel in terms of flow, with a recirculating fan and a medium cooler; Fig. 3 a schematic sectional view through a filter device along line III-III in Figure 2 , concerning a process step for filtering a medium flowing through the filter device; Fig. 4 a sectional view according to Figure 3 , however, concerning an offset cutting plane; Fig. 5 one of the Figure 3 corresponding sectional view through the filter device, relating to a process step for evacuating the interior of a filter housing; Fig. 6 a subsequent view to Figure 5, concerning a process step for cleaning a filter in the filter housing of the filter device; Fig. 7 a subsequent illustration to Figure 6after completion of the cleaning process and transfer of filter material into a filter material collection chamber; Fig. 8 the magnification of area VIII when the filter material collection chamber is removed from the filter housing; Fig. 9 the filter material collection chamber in a perspective view with an attached lid; Fig. 10 the filter material collection chamber removed from the filter unit in a position attached to a transport vehicle as it approaches a receiving device; Fig. 11 the filter material collection chamber placed in the receiving device; Fig. 12 the filter material collection chamber pivoted into a mixing position in the receiving device; Fig. 13 the mixing position of the filter material collection chamber in a schematic vertical section view; Fig. 14 a perspective cross-sectional view through the filter material collection chamber; Fig. 15 a subsequent view to Figure 12 , concerning the filter material collection chamber during passivation of the chamber contents; Fig. 16 one of the Figure 13 corresponding sectional view, concerning a position of the collection chamber during passivation according to Figure 15 ; Fig. 17 the receiving device with the after passivation in the parking orientation according to Figure 11 returned filter material collection chamber; Fig. 18 the filter material collection chamber filled with passivated filter material in a further arrangement position on the transport vehicle during the collection of the collection chamber from the receiving device; Fig. 19 a subsequent representation to Figure 18 after turning the filter material collection chamber into an emptying position; Fig. 20 a subsequent illustration to Figure 19 after lifting the filter material collection chamber; Fig. 21 a situation during the process of moving the filter material collection chamber towards a transport container using the transport vehicle; Fig. 22 a situation during the process of docking the filter material collection chamber to the transport container; Fig. 23 the emptying situation; Fig. 24 the subsequent situation Figure 23, after emptying; Fig. 25 the emptied filter material collection chamber in the transport vehicle after turning back to the starting position and approaching the receiving device again to fill the collection chamber with solid material; Fig. 26 the filling situation after docking the collection chamber to a storage container provided in the receiving device; Fig. 27 the situation after the collection chamber has been filled with solid material and the filter device has been lowered; Fig. 28 the return transport situation of the collection chamber filled with solid material back to the filter device; Fig. 29 a schematic sectional view through the filter device according to Figure 3 , after rearranging the filter material collection chamber on the filter unit. Description the embodiments

[0048] The presentation and description initially refers to Figure 1, a metal printing device 1 with an associated filter module 3 comprising a plurality of filter devices 2.

[0049] The metal printing device 1 essentially comprises a cabin 4 in which the metal printing process can be carried out. Here, a desired component is produced layer by layer from fine metal powder using selective laser melting under the influence of a laser beam. Production can be carried out directly from so-called 3D CAD data, enabling the manufacture of fully functional components from high-quality metals.

[0050] Besides the in Figure 1 The laser device 5, which is only shown schematically, is essentially an application device for applying a layer of metal powder, part of the printing device, and also a powder storage container and a powder collection container into which excess particles can be wiped off.

[0051] The metal part is manufactured in a completely enclosed cabin 4, which may optionally be equipped with a door 6 or the like to close the cabin 4.

[0052] Regarding the manufacturing process, reference is made, for example, to the DE 10 2017 206 792 A1 cited at the beginning.

[0053] During the printing process, the atmosphere in the cabin 3 is preferably regenerated. For this purpose, a gaseous process gas 7, preferably a protective gas such as argon or nitrogen, is preferably blown into the cabin 4 and simultaneously extracted using a recirculation method. A blower 8, for example a recirculating blower, is preferably used for this purpose. The blower 8 can be a so-called side-channel blower or the like.

[0054] In the illustrated embodiment, the blower 8 is arranged in the filter module 3 in spatial proximity to the filter devices 2.

[0055] With regard to the method for cleaning the filter as well as the design of the filter device, reference is made to the aforementioned DE 10 2019 132 349 A1. The content of this patent application is hereby fully incorporated into the disclosure of the present invention, also for the purpose of including features of this patent application in the claims of the present invention.

[0056] As further details can be seen in the schematic representation in Figure 1 As can be seen, the blower 8 is flow-connected to the interior of the cabin via a pressure line 9 and a suction line 10 as well as an inlet 55 and an outlet 56.

[0057] Here, the pressure line 9, starting from the blower 8, can be connected directly, if necessary, as in Figure 2As shown, the pressure line 9, with an intermediate medium cooler 11, leads into the cabin 3, preferably to a ceiling area of ​​the cabin 3. During operation, the pressure flow of the medium 7 in the pressure line 9 follows a direction a.

[0058] At least one filter device 2 is integrated into the suction line 10, corresponding to a line upstream of the blower 8 in the direction of flow of the process gas 7. According to the illustrated embodiment, several filter devices 2, here three, can be provided.

[0059] The filter devices 2, together with the blower 8 and the optionally provided medium cooler 11, and optionally with a pre-separator and / or a fine filter, can be arranged together in the filter module 3. This filter module 3 can have a filter housing 14 which includes the aforementioned elements. Only two interfaces are required, one each for the pressure line 9 and the suction line 10.

[0060] A pre-separator, if provided, can be located upstream of the single filter unit 2 or upstream of the multiple filter units 2 when viewed in the direction of flow of the process gas 7, while a fine filter can be located downstream of the filter unit 2 in the direction of flow.

[0061] In suction line 10, a typical manufacturing process and the associated process gas circulation result in a direction b of the suction flow.

[0062] The filter devices 2 are preferably provided in substantially identical configurations, each having a medium inlet 15 and a medium outlet 16. Each filter device 2 is preferably directly connected to the suction line 10 via its respective medium inlet 15. The medium outlets 16 of the filter devices 2 open into a suction transfer line 17, which, optionally with the interposition of the fine filter, leads to the blower 8 (see in particular...). Figure 2 ).

[0063] The fine filter can, for example, also be provided at the end of the pressure line 9 in the direction of flow, and possibly also in the direction of flow after the medium cooler 11.

[0064] The Figures 3 and 4Each figure shows a vertical section view through one of the filter devices 2 in regeneration mode, in which the medium 7 discharged from the cabin 4, for example contaminated by soot, is filtered, with reference to the usual operating position of the filter device 2.

[0065] As for example from the sectional view in Figure 3 As can be seen, the filter device 2 can have an approximately circular cylindrical filter housing 18, with a circumferential housing wall 19 and a housing roof 20. The housing bottom 21 can be funnel-shaped with a central bottom opening 22, to which a sluice section 23 can be connected to a filter material collection chamber 24 that can be removed from the filter housing 18.

[0066] Between the filter housing 18 and a channel section 12 formed in the lock section 23, a lock valve 51 is arranged which is loaded into a closing position by a compression spring 54.

[0067] On the underside of the housing cover 20, a filter 26 projecting into the interior 25 of the filter housing 18 can be arranged, as shown. The filter wall of this filter can be, as also shown, tubular or circular-cylindrical, with a central longitudinal axis x that, in the usual arrangement, is aligned along a vertical line. According to the illustrated embodiment, the longitudinal axis x of the filter 26 can simultaneously form the central longitudinal axis of the entire filter housing 18.

[0068] The filter 26 is surrounded at a distance from the outer surface 28 of the filter wall 27 by a guide wall 29, preferably oriented concentrically to the longitudinal axis x. This guide wall 29, like the filter 26, is suspended from the underside of the housing roof 20 and preferably connected to it in a flow-tight manner. The annular space 35 formed between the guide wall 29 and the filter wall 27 is open in the axial direction towards the interior 25, while the corresponding end face 30 of the filter 26, which faces downwards during normal operation, is designed to be impermeable to the flow, in particular to the process gas 7. Filter material 32 separated in this way can fall into the collection chamber 24 solely by gravity through the bottom opening 22 of the housing bottom 21, passing through the channel section 12 of the lock section 23.A lock valve 51 provided between the lock section 23 and the receiving chamber of the collection chamber 24 is held in an open position.

[0069] The inlet opening 31 of the medium inlet 15 can, preferably, be provided in the housing wall 19, so that an at least approximately tangential flow of the medium 7 into the interior 25 of the filter housing 18 can occur, thereby initially achieving a vortex-like pre-separation of filter material 32 (compare Figure 3 The filter device 2 initially acts in the manner of a cyclone separator, in which the process gas flow is guided in a vortex-like manner from the inlet opening 31 in the annular space resulting between the guide wall 29 and the housing wall 19.

[0070] The outlet opening 33 of the medium outlet 16 can be provided in the area of ​​the housing ceiling 20 according to the illustrated embodiment, in particular, and preferably, centrally, receiving the longitudinal axis x and further associated with the filter interior 34 enclosed by the filter wall 27.

[0071] As a result of the suction flow that occurs during normal operation (filter operation) of the filter device 2, the process gas 7 drawn into the interior 25 is, after the vortex-like deflection, directed downwards towards the front surface 30 of the filter 26 and drawn from below into the annular space 35 between the filter wall 27 and the guide wall 29, resulting in a penetration of the filter wall 27 from the outer surface 28 to the inner surface 36 of the filter wall 27 (see arrows d in Figure 4 ), so that the filtered medium 7 reaches the filter interior 34 and leaves the filter device 2 via the outlet opening 33 (compare Figure 4 ).

[0072] Filter material 32 separated in this process may be adhered to the filter wall 27. Any filter material 32 falling through the annular space 35 during this filtration process is preferably collected in the filter material collection chamber 24.

[0073] The filter material collection chamber 24 is filled with a solid material 57, for example in the form of glass granules, as a fire retardant B before commissioning, so that in particular the bottom of the collection chamber 24 is covered by this fire retardant B.

[0074] As can be seen from the sectional views, for example in the Figures 3 and 4The medium inlet 15 and the medium outlet 16 can each be equipped with a shut-off valve 37 and 38, respectively, to isolate the filter unit 2 from the regeneration process by isolating it from the suction line 10 and the suction transfer line 17. In this state, the regeneration of the process gas 7, while the metal pressure unit 1 remains in operation, is handled solely by the other filter units 2 of the filter module 3. This ensures at least nearly continuous operation of the metal pressure unit 1 even in the event of a failure or deliberate isolation of a filter unit 2, for example, for cleaning.

[0075] For this purpose, the preferably pneumatically actuated shut-off valves 37 and 38 of the medium inlet 15 and the medium outlet 16 are moved into a closed position. The control of the shut-off valves 37 and 38 can, preferably, be effected via control electronics 39 (not shown in detail), which can also be part of the filter module 3.

[0076] To clean the filter 26 in the filter unit 2 and to remove the filter cake that settles on the filter wall 27 during the filtration of the process gas 7, the filter unit 2 must be put into regeneration mode. For this purpose, the filter unit 2 can, as described above, first be removed from the flow of process gas or isolated from the lines by closing the shut-off valves 37 and 38 and thus closing the medium inlet 15 and the medium outlet 16.

[0077] To prepare for the cleaning process, a vacuum is first created in the filter housing 18 using a separate pump, in particular a vacuum pump 41. This evacuates the interior 25 of the filter housing 18 and also the interior of the filter material collection chamber 24, which is open to this interior 25 (see schematic diagram in [reference]). Figure 5 - Arrow e).

[0078] The vacuum pump 41, which may preferably also be part of the filter module 3, may, and preferably, be an oil-lubricated vacuum pump, such as that known from DE 10 2015 107 721 A1.

[0079] Once a vacuum of, for example, 500 mbar down to, for example, 1 mbar is reached in the interior space 25 (detectable via a pressure sensor), the suction process via the vacuum pump 41 is stopped by the control electronics 29, and subsequently an discharge valve 42, located, for example, in the area of ​​the airlock section 23 between the filter housing 18 and the filter material collection chamber 24, is closed. The discharge valve 42 interrupts the line connection between the interior of the filter housing 18, which contains the filter 26, and the interior of the filter material collection chamber 24.

[0080] A cleaning medium 45 is introduced via a separate cleaning medium reservoir 43, which can also be part of the filter module 3, towards the filter wall 27 via a cleaning line 44 to clean the filter 26. The introduction of the cleaning medium 45 can be triggered by a preferably electrically actuated control valve 46 (see Figure 6The control valve 46 can be controlled via the control electronics 39.

[0081] The flushing medium 45 can be introduced via, for example, multiple flushing medium inlets 47 and 48 arranged around the longitudinal axis x in the housing roof 20. According to the illustrations, the flushing medium 45 is introduced into the filter interior 34 via the flushing medium inlets 48 in such a way that it flows through the filter wall 27 in a direction c opposite to the flow direction of the medium 7 in normal filter operation (direction d - see illustrations). Figure 4 ) permeates the filter wall 27. This results in the rinsing medium 45 penetrating the filter wall 27 from the inner surface 36 towards the outer surface 28.

[0082] Simultaneously or at a later time than the flow described above, the rinsing medium 45 is introduced via the radially outer rinsing medium inlet 47 essentially along the outer surface 28 of the filter wall 27 (direction f) in order to reliably remove the filter material 32, which is loosened in particular via the portion of the rinsing medium that passes through the filter wall 27 from the inside to the outside, from the intake area towards the bottom of the housing 21.

[0083] The introduction of the rinsing medium 45 can be achieved solely by suction due to the negative pressure prevailing in the interior 25 of the filter housing 18 relative to the surroundings, but can also be achieved, if necessary, by blowing the rinsing medium 45 into the interior 25. The negative pressure in the interior 25 ensures a favorable flow of the rinsing medium over and through the filter wall 27.

[0084] At the end of the cleaning process, the pressure in the interior 25 of the filter housing 18 is preferably the same as in the connected lines (suction line 10 and suction transfer line 17), so that when the shut-off valves 37 and 38 are opened, which in this example achieves the reintegration of the cleaned filter device into the filtration process, no backflow against the usual flow direction of the process gas 7 takes place.

[0085] The same medium is preferably used as the rinsing medium 45 that is also used as a process gas for removing impurities in the cabin 4 of the metal pressure device 1. Thus, argon and / or nitrogen are preferably used as the rinsing medium 45.

[0086] By re-evacuating, a second cleaning process can be carried out immediately after the first cleaning process, if necessary.

[0087] Upon completion of the cleaning process and the associated pressure equalization in the interior 25 of the filter housing 18, a pressure difference arises between the interior 25 and the interior of the filter material collection chamber 24. Opening the discharge valve 42 causes the filter material 32, which was loosened during the cleaning process and preferably collected at the bottom of the housing, to be drawn into the filter material collection chamber 24. Similarly, simply opening the discharge valve 42 triggers the transfer of the loosened filter material 32 into the collection chamber (see Figure 1). Figure 7 - Arrow g). The suction process continues until pressure equalization occurs between the interior 25 and the collection chamber 24. Furthermore, filter material 32 can also trickle into the collection chamber 24 due to gravity.

[0088] From this collection of filter material according to Figure 7The filter device 2 can be reintroduced into the filter circuit of the filter module 3 by opening the shut-off valves 37 and 38 in the medium inlet 15 and in the medium outlet 16 (see Figure 15 ).

[0089] To dispose of the filter material 32 collected in the filter material collection chamber 24, preferably from a plurality of filter cleaning processes, the filter material collection chamber 24 can be removed from the filter housing 18. For this purpose, the tubular free end of the lock section 23 can be designed to receive a flow-tight socket section 49 of the collection chamber 24 (compare Figure 8 The chamber opening 50 surrounded by the sleeve section 49 is preferably closable by means of the sluice valve 51. A valve cone 52 directed towards the sluice section 23 can be positioned in the docking position of the collecting chamber 24 on the filter housing 18 according to Figure 7, be directly supported by a hold-down device 53 in the area of ​​the lock section 23, so that the lock valve 51 is held in a position releasing the chamber opening 50. The hold-down device 53 can extend in a finger-like manner, as shown in the illustrations, thereby passing through the channel section 12.

[0090] In the course of removing the filter material collection chamber 24 from the lock section 23, for example by unscrewing or further for example after releasing a locking mechanism, the valve cone 52 loses its support on the retainer 53 of the lock section 23, as a result of which the lock valve 51 automatically falls into a position closing the chamber opening 50 under pressure from the compression spring 54.

[0091] Preferably, the filter material collection chamber 24 is removed with the discharge valve 42 closed, so that when the collection chamber is removed, the atmosphere in the interior 25, essentially formed by the medium 7, is maintained. Furthermore, by sealing off the interior of the filter material collection chamber 24 with the discharge valve 51, the filter material 32 contained therein remains under a process gas atmosphere, specifically an atmosphere formed by the process gas 7 or the rinsing medium 45.

[0092] After a predetermined number of cleaning cycles, the filter material collection chamber 24 is removed from the filter unit 2 and its contents (collected reactive filter material 32 and solid material 57 or fire retardant B) are disposed of. A passivation station for the filter material 32 is located upstream of this disposal.

[0093] Furthermore, the collection chamber 24 can have rod-like handling elements 59 on its outer wall, for example in the area of ​​the socket section 49, oriented transversely to the longitudinal axis x. These handling elements 59 can be used to transport the collection chamber 24 manually or by means of a transport device 60. In addition, a section of the handling elements 59 can be designed as a sliding handle 77 transversely to the longitudinal axis x, for acting on a slide 73 that serves to lock the filter material collection chamber 24 to the lock section 23. By pulling the handle 77 radially outwards – with respect to the longitudinal axis x – the locking mechanism can be released.

[0094] As in the Figures 10 and 18 to 28 As shown, transport of the collection chamber 24 taken from the filter device 2 using a forklift-like driving device 60 is preferred.

[0095] The transport device 60 preferably has a ground-level chassis 61 with wheels 62. A lifting mast 63 is mounted on the chassis 61 in a substantially vertical orientation. Fork tines 64, which are substantially horizontally oriented and vertically displaceable, are arranged along this mast and are driven, for example, by a lifting chain. The fork tines 64 are designed to securely grip the collection chamber 24, in particular its handling parts 59. For example, a clamping or locking mechanism may be provided when the handling parts 59 are gripped.

[0096] As can be seen, the transport device 60 detects the collection chamber 24 in the area of ​​the handling parts 59, as shown in Figure 10. This detection allows any locking mechanism of the collection chamber 24 on the lock section 23 of the filter device 2 to be released, so that the collection chamber 24 can then be transported by means of the transport device 60.

[0097] In the course of removing the filter material collection chamber 24 from the lock section 23 or, if necessary, immediately afterwards, the chamber opening 50 can be closed with a separate cover 58 by actuating and repositioning the slide 73.

[0098] The lid 58 is designed to close the chamber opening 50 of the filter material collection chamber 24, for which purpose the lid 58 first and essentially has a cup section 13 with an outer diameter adapted to the diameter of the chamber opening 50 in the area of ​​the socket section 49, which is preferably integrally and further preferably of a single material formed on the underside of a plate-like cover section 82 which, in the closed position, rests on the facing collar 76 of the socket section 49 (compare Figure 9 ).

[0099] The lid 58 is perforated by a pipe 83 which connects the interior of the collection chamber 24 - when the sluice valve 51 is open - via a further connected pipe to a pump, for example a vacuum pump.

[0100] A shut-off valve 84 can be provided in the pipeline 83, and is also preferred.

[0101] The filter material collection chamber 24 is preferably fed to a station 65. This station 65 preferably serves to passivate the contents of the collection chamber and can, furthermore, as is also preferably shown, have a supply of fire retardant for filling the collection chamber 24 before commissioning the collection chamber 24.

[0102] Station 65 can thus have a receiving device 66 into which the filter material collection chamber 24, preferably transported by means of the vehicle 60, can be placed.

[0103] The receiving device 66 can be formed in a grid box shape, preferably having a base 67 and an insertion or removal opening directed towards a front of the station 65.

[0104] Furthermore, the receiving device 66 is pivotably mounted on the base frame 68 of the station 65 about a preferably horizontally oriented pivot axis y. The pivot axis y preferably extends transversely to an approach direction r of the vehicle 60 during approach to the station 65 (compare Figure 10 Furthermore, the pivot axis y preferably extends substantially centrally to, through, or below the mounting surface 67. The corresponding axis body is supported on a crossbeam centrally located on the mounting surface 67 and is also mounted in this area.

[0105] The basic position of the receiving device 66, in which basic position the placement of the collection chamber 24 on the base 67 or the removal of the collection chamber 24 is also carried out, is preferably limited by a stop, as is, if necessary, a pivot position according to Figure 12 In this pivot position, a pivoting of the collecting chamber 24 about the pivot axis y, which is oriented transversely to its longitudinal axis x, of about 45 degrees can be achieved (see also Figure 13).

[0106] In this pivoted position, the collecting chamber 24, with its preferably circular cylindrical outer wall, can bear against at least one drive roller 69 and one support roller 70. The geometric axes of rotation of these rollers 69 and 70 are preferably perpendicular to the plane of the base 67 and thus parallel to the longitudinal axis x of the collecting chamber 24.

[0107] The drive roller 69 can be actively driven via a shaft 71, for example (as can be seen in particular from the illustrations in the Figure 12 and 13 (as can be seen) by an electric motor 72. The collecting chamber 24, which is supported on the rollers in particular by its weight, can thus be rotated about the longitudinal axis x, especially in the pivot position, according to the drive of the drive roller 69.

[0108] As can be seen in particular from the schematic representation in Figure 16 As shown, when the collection chamber 24 is rotated around its longitudinal axis x in the pivot position, a substantially uniform mixing of solid material 57 and filter material 32 is achieved in a first mixing cycle.

[0109] What next, in particular, Figure 14As shown, a mixing blade 85 can be provided in the collection chamber 24 by inserting and fastening a correspondingly shaped sheet metal part, which, with reference to a substantially circular plan of the collection chamber 24, penetrates it approximately along a diameter line and extends from the chamber floor 86 approximately over the axial height of a circular cylindrical chamber section.

[0110] The mixing blade 85 is preferably attached to the inside of the chamber wall, for example by welding.

[0111] With regard to its planar extent, the mixing blade 85 preferably has a central opening 87. This opening can have an oval plan shape, with a shorter axis extending in the direction of the longitudinal axis x and a longer axis extending transversely to it, wherein the dimension of the longer axis can correspond approximately to 0.5 to 0.8 times the free inner diameter dimension of the collection chamber 24 in the area of ​​the mixing blade 85 and the dimension of the shorter axis approximately to 0.5 to 0.9 times the longer axis.

[0112] After this first mixing cycle, or possibly in superposition thereof, a vacuum is preferably generated in the collection chamber 24 via the pipeline 83, and furthermore, in particular, via a vacuum pump connected thereto, which is further preferably a component of the station 65, especially the receiving device 66. The associated shut-off valve 84 is open for this purpose.

[0113] At least in this evacuation situation, the chamber-side lock valve 51 is preferably held in the open position, for which the cover 58 in the attached position acts on the valve cone 52 via a hold-down device 53 against the restoring force of the valve-side compression spring 54.

[0114] Once a sufficiently large negative pressure is reached in the collection chamber 24, the vacuum connection is closed and a flow connection to the environment is opened via a fine throttle and the rotation process of the pivoted collection chamber 24 is restarted, provided that it was stopped for evacuation.

[0115] Due to the intensive mixing with the comparatively fine solid material 57, only a small amount of filter material 32 reacts at the resulting surface 78 (compare Figure 16) with the atmospheric oxygen flowing in very slowly and in a controlled manner from the surrounding atmosphere, for example via the fine throttle. Accordingly, the filter material 32 is successively passivated in the collection chamber 24.

[0116] By the proposed and described method, a large proportion of the fire-prone filter material 32 is hermetically sealed by the fire retardant B, in particular the solid material 57, when the filter material collection chamber 24 is arranged in the mixing station. Only a small fraction of the surface of the filter material-solid material mixture reacts with atmospheric oxygen at any given time. The passivation reaction proceeds accordingly slowly so that the temperature increase occurring in the collection chamber 24 during the reaction remains comparatively low, allowing the resulting heat to be dissipated to the environment solely through the housing walls.

[0117] With an exemplary intake volume of the filter material collection chamber 24 of approximately 20,000 cm³, such passivation can be carried out by mixing and simultaneous supply of atmospheric oxygen over a period of, for example, 2 hours up to 12 hours or more.

[0118] Upon completion of this passivation process, the rotary drive is stopped and the receiving device 66 is pivoted back to its starting position around the pivot axis y, so that the collection chamber 24 is free to stand on the base 67 and ready for further transport.

[0119] This further transport to a transport container 74 is also preferably carried out via the transport vehicle 60. For this purpose, the collection chamber 24 is preferably again engaged by the forks 64 in the area of ​​the handling parts 59. Subsequently, optionally during the movement of the transport vehicle 60 towards the transport container 74, the forks 64 are pivoted together with the collection chamber 24 about a geometric pivot axis z directed transversely to the vertical extension of the lifting mast 63 by preferably 180 degrees, so that the chamber opening 50 of the collection chamber 24 then points downwards (compare Figure 19 ).

[0120] If necessary, after raising the fork tines 64 and the collection chamber 24 carried above them along the lifting mast 63 in a direction h vertically upwards, the transport container 74 is approached, into which the contents of the collection container 24 are emptied.

[0121] The transport container 74 is provided in the area of ​​its filling opening (not shown) with a pipe-like adapter section 75, which is preferably designed for sealing interaction with the socket section 49 or the chamber opening 50 of the collection chamber 24. Preferably, this enables a tight connection, such as that which essentially occurs, for example, between the collection chamber 24 and the lock section 23 of the filter device 2.

[0122] The adapter section 75 is connected according to the schematic diagram in Figure 24By appropriately bringing the collection chamber 24 into position using the transport device, the collection chamber 24 is docked, so that the passivated filter material 32, mixed with solid material 57, which is received in the collection chamber 24, can preferably be transferred via the chamber opening 50 into the space 79 of the transport container 74, which is in any case sealed off from the surrounding atmosphere, by gravity alone.

[0123] The collection chamber 24, which has been emptied, is returned to station 65 by means of the transport device 60 after the collection chamber 24 has been turned back to its starting position, but now for refilling the collection chamber 24 with solid material 57 (see below). Figure 25 ).

[0124] For this purpose, a storage container 80 containing fire retardant B, for example solid material 57, can be provided in station 65 adjacent to the receiving device 66, with a vertically downward-pointing, preferably lockable adapter section 81. The collection chamber 24 is brought towards the underside of the storage container 8 accordingly, whereby finally, by lifting the collection chamber 24 vertically upwards, docking of the collection chamber 24 with its socket section 49, optionally with the lid-side nozzle 76, is achieved on the adapter section 81.

[0125] If necessary, by targeted release, for example by sliding the adapter section 81 open, a preferably predetermined quantity of solid material 57 can be transferred from the storage container 80 into the collection chamber 24 preferably under gravity dependence (compare arrow k in figure 26).

[0126] The newly filled collection chamber 24 with solid material 57 can then be opened, if necessary after lowering in accordance with Figure 27 , transported back to the filter unit 4 by means of the transport vehicle 60 and rearranged there (compare Figures 28 and 29 ).

[0127] During the passivation and disposal process, the filter unit 2 can also be equipped with an exchange collection chamber 24 to enable further filter operation.

[0128] Insofar as reference is made above to process gas, if the filter device is used in connection with a different medium to be cleaned, i.e., in particular, if used in a context other than with a metal pressure device, the process gas may be a different medium.

Claims

1. A method for cleaning a filter (26) in a filter device (2) having a filter housing (18) and the filter (26) located therein, the filter device (2) having a filtered material collecting chamber (24) for receiving filtered material (32) which accumulates in the course of cleaning the filter (26), wherein the filtered material collecting chamber (24) is filled with a fire prevention agent (B) before a first receipt of filtered material (32), for which purpose the filtered material collecting chamber (24) is filled with a solid material (57) over part of the volume of the filtered material collecting chamber (24), characterized in that in the course of a removal of the filtered material collecting chamber (24) from the filter device (2), a targeted exchange of a chamber atmosphere for the surrounding atmosphere is carried out, wherein in connection with an inflow of atmospheric air, a mixing movement of the filtered material collecting chamber (24) is carried out for mixing the filtered material (32) with the solid material (57).

2. The method according to claim 1, characterized in that the filtered material collecting chamber (24) is filled with a gas for fire prevention.

3. The method according to claim 1 or 2, characterized in that the filtered material collecting chamber (24) is filled with a protective gas for fire prevention.

4. The method according to one of the preceding claims, characterized in that the solid material (57) is granular.

5. The method according to one of the preceding claims, characterized in that the solid material (57) is glass-like.

6. The method according to one of the preceding claims, characterized in that the filtered material collecting chamber (24) is removed from the filter device (2) after a predetermined filling level of filtered material (32) in the filtered material collecting chamber (24) is reached and the protective gas is exchanged for atmospheric gas.

7. The method according to claim 6, characterized in that the exchange, with regard to a volume of the filtered material collecting chamber (24) receiving a filtered material (32) of 10,000 to 25,000 cm3 or more, is carried out over a period of time ranging from 2 hours up to 12 hours or more.

8. The method according to one of the preceding claims, characterized in that the filtered material collecting chamber (24) removed from the filter device (2) is connected to a transport container (74), and in that the filtered material (32) is transferred directly into a space (79) of the transport container (74) which, in any case, is shut off from the atmosphere.