WO2025162718A2 - Method for passivating a filter condensate, and reactor device for passivating the filter condensate - Google Patents

Abstract

The invention relates to a method for passivating a filter condensate (3) from a filter device (2) provided in a gas guide of an additive manufacturing machine by carrying out a chemical reaction between the filter condensate (3) and an oxidizing agent in a reactor device (1). The reactor device (1) preferably has a supply line (44), a reactor chamber (5) with a filter device connection (6) for establishing a transportable connection between the reactor device (1) and the filter device (2), and a collecting chamber connection (8) for establishing a transportable connection between the reactor device (1) and a collecting chamber (9) for receiving passivated filter condensate (3). The preferably provided supply line (44) and/or the reactor chamber (5) are designed to be pressure-resistant, the preferably provided supply line (44) and/or the reactor chamber (5) are separated from the surroundings in order to carry out the passivation, and an ignition process is carried out. Furthermore, a first quantity of filter condensate (3) and a second quantity of oxidizing agent are introduced in portions into the preferably provided supply line (44) and/or into the reactor chamber (5). The method is characterized in that in order to carry out the passivation, the first quantity is stoichiometrically matched to the second quantity in such a way that an explosive mixture is achieved, and the passivation is carried out by triggering an explosion.

Description

Description Method for passivating a filter condensate and reactor device for passivating the filter condensate Technical field _{[0001] The invention relates firstly to a method for passivating a} filter condensate from a filter device arranged in a gas duct of a device for additive manufacturing by carrying out a chemical reaction between the filter condensate and an oxidizing agent in a reactor device, wherein the reactor device preferably has a feed line, a reactor chamber with a filter device connection for establishing a transportable connection between the reactor device and the filter device and a collection chamber connection for establishing a _{transportable connection between the reactor device and a collection} chamber for receiving passivated filter condensate, wherein the preferably provided feed line and/or the reactor chamber are designed to be pressure-resistant, the preferably provided feed line and/or the reactor chamber are separated from the environment to carry out the passivation and an ignition is carried out, wherein furthermore a first amount of filter condensate and a second amount of oxidizing agent are introduced in portions into the preferably provided supply line and/or into the reactor chamber. _{[0002] Furthermore, the invention relates to a method for passivating a filter} condensate from a filter device arranged in a gas duct of a device for additive manufacturing by carrying out a chemical reaction between the filter condensate and an oxidizing agent in a reactor device, wherein the reactor device comprises a reactor chamber with a

31257N1PCT – 31.10.2024 a filter device connection for establishing a transportable connection between the reactor device and the filter device, preferably by means of a supply line, and a collection chamber connection for _{establishing a transportable connection between the reactor device and} a collection chamber for receiving passivated filter condensate, wherein the reactor space can be designed to be pressure-tight, is separated from the environment to carry out the passivation and an ignition is carried out for passivation, wherein process gas conveyed further in the gas line, after leaving a production chamber, also has second, unaltered particles in addition to first particles chemically modified during additive manufacturing. _{[0003] Furthermore, the invention relates to a reactor device for passivating} a filter condensate from a filter device arranged in a gas duct of a device for additive manufacturing by carrying out a chemical reaction between the filter condensate and an oxidizing agent, _{wherein the reactor device has a reactor chamber and preferably a supply line leading to the reactor chamber, further comprising a reactor chamber with a filter device connection for establishing a fluidic} connection between the reactor device and the filter device _{and a collection chamber connection for establishing a} fluidic connection between the reactor device and a collection chamber for receiving passivated filter condensate. State of the art _{[0004] In devices for additive manufacturing, in particular in devices for printing metal-based parts, a gas, a process gas, is} usually circulated and is supplied from a cabin, which is also referred to as a process chamber, in which the additive manufacturing

31257N1PCT – 31.10.2024 is carried out, into a filter device and then back into the process chamber. For example, _{reference can be made to WO 2021/104927 A1 (US 2022/0362691 A1). When additive manufacturing is carried out} by laser welding, for example, laser welding fumes are produced which must be filtered. _{[0005] The gas can in particular be a protective gas, an inert} gas such as argon or, for example, nitrogen. _{[0006] During additive manufacturing, unused} particles, in particular (metal) particles, also _{referred to below as raw powder, and any reaction products or spalling products or ejections from the melt pool are carried out of the process chamber by means of the process} gas. The spalling products and/or ejections from the melt pool are also _{referred to collectively below as splash, splatter. The spatter and any smoke generated, particularly laser welding smoke during laser manufacturing, are carried out} and separated in the filter device. An agglomerated metal powder _{condensate, also referred to here as filter condensate, forms in the filter device, particularly from the laser welding smoke} . Since the components of the filter condensate do not come into contact with oxygen during manufacturing, they can be highly reactive. Contact with oxygen, _{particularly during disposal, can therefore pose a fire and explosion hazard. The filter condensate is preferably removed from a filter of the filter device either pressure-dependently or at regular} intervals, for example by a pressure surge, and then _{fed into a reactor device for passivation. The pressure surge can be carried out in particular with an inert gas} such as nitrogen or argon or the like.

31257N1PCT – 31.10.2024 _{[0007] The reactor device as described here is operated in particular} in combination with an upstream filter device and a downstream collection chamber for receiving the passivated filter condensate. The filter condensate, as it is separated at the filter device, is usually still highly active and can lead to fires or explosions. Passivation is therefore necessary. _{[0008] A reactor device of a filter device known as a separable chamber} , in which reactor device filter condensate is passivated, is known _{, for example, from DE 102021116264 A1 and WO 2022/268497 A1. Furthermore, reference is made to DE 102020000501 A1 (US 2023/0142672 A1) and the unpublished DE 102023126014} . _{[0009] In the known methods and devices for passivating} filter condensate, a process control is required which avoids explosive development as far as possible. For example, flooding with oil or water or _{the addition of neutralizing agent has already been proposed, even when} filter _{condensate has already been transferred from the passivation device to the collecting device. This is associated with a residual risk on the one hand, and can also cause considerable costs on the other} . Summary of the invention _{[0010] Starting from a prior art, as known, for example, from the aforementioned DE 102020000501 A1, the object of the invention is to provide a} method for passivating filter condensate and a reactor device for passivating the filter condensate, in which or in which the desired passivation can be achieved as effectively and simply as possible.

31257N1PCT – 31.10.2024 _{[0011] With regard to the method, this object is initially and essentially} achieved in that, in order to carry out the passivation, the first quantity is stoichiometrically adjusted to the second quantity in such a way that an explosive mixture is achieved and that the passivation is carried out by triggering an explosion. _{[0012] The stoichiometric adjustment means that the mixture of the} first and second quantities is in the stoichiometric range that is usually explosive, as is known, for example, with regard to dust explosions. This refers to a ratio of oxygen to combustible or explosive components. Preferably, the adjustment is such that the mixture _{is clearly in the range required for the explosion. The aim is to achieve as complete combustion or oxidation as possible (even in a first explosion)} . On the other hand, increased pressure due to an excessively high oxygen content should _{be avoided. The passivation is accordingly carried out by triggering} the explosion. According to the method described here _{, the path is deliberately, deliberately, and systematically taken to trigger an explosion for passivation. The already existing property of the filter condensate to be explosive is deliberately used for passivation. In contrast to the known measures, the reactivity of the condensate is not masked by the addition of materials or the} condensate is not sufficiently demixed by additives, but the reactivity of the condensate or the individual _{particles contained therein is deliberately reduced to a level that is no longer relevant. [0013] The stoichiometric adjustment does not mean that the exact stoichiometric ratio required to trigger the explosion is necessarily,} although preferably, produced. It can also be used in certain

31257N1PCT – 31.10.2024 _{Limits a sub- and in particular a super-stoichiometric ratio can be set. In additive manufacturing with titanium powder, for} example, with regard to a titanium filter condensate obtained in this way, with a _{quantity of 0.2 g (corresponding to 1 cm³) of titanium filter condensate, an air requirement of 2.22 dm³ results. [0014] The method described here is accordingly associated with the advantage} that, with the exception of the second quantity, no additives have to be introduced. Since, as explained further below, the second quantity can preferably be air, in particular ambient air, this _{provides a simple and cost-effective method for carrying out the passivation.} Due to a stoichiometrically required amount of oxygen _{, a required amount of air can also be determined when the oxygen is provided by air, for example ambient air} . _{[0015] In particular, a comparatively low energy input is also required to achieve the passivation. Since one or possibly several explosions also very effectively convert flammable or explosive components} in the filter condensate into a neutral state, a final passivation in the reactor chamber can also be _{achieved. No special precautionary measures need to be taken in the collection container} . _{[0016] With regard to a further method, which does not necessarily} require the implementation of a controlled explosion, but which is preferably provided, a separation device is arranged further upstream of the filter device to separate second, chemically unchanged particles.

31257N1PCT – 31.10.2024 _{[0017] This advantageously allows for more predictable passivation} to be carried out. The filter condensate to be passivated has a more homogeneous composition. In particular, when proceeding with regard to a method described further here, the second quantity required to carry out a controlled explosion can also be determined more precisely _{. The required or at least achievable mixing ratio} between the first and second quantities can be adjusted in a more controlled manner. _{[0018] With regard to the reactor device, the object is initially and} essentially achieved in that the feed line and/or the reactor chamber and the ignition device _{are provided for carrying out a controlled explosion and, preferably, in that a reactor base is designed to be displaceable between a} first and a second operating position, wherein the reactor base forms part of the reaction chamber in the first operating position and part of the discharge chamber in the second operating position, and the subdivision can be removed during the displacement of the reactor base. _{[0019] The pressure-resistant design of the supply line and/or the reactor} chamber accordingly means that the walls are designed such that _{the supply line and/or the reactor chamber are explosion-proof. This is particularly true with regard to the large number of explosions for which the reactor device is designed. This may also be true with regard to explosions expected in immediate succession, as explained below, over a realistic operating period. Furthermore, this may mean that the} supply line and/or the reactor chamber must in any case withstand a pressure of more than _{2 bar up to 8 or 10 bar, possibly even higher up to approximately 15 bar} or more, and this repeatedly over an intended or designed operating period.

31257N1PCT – 31.10.2024 _{[0020] The reactor chamber is divided by the reactor floor into a reaction chamber} and a spatially separate discharge chamber. _{[0021] Accordingly, it is also important for the process that the explosion, which in this respect is a preliminary explosion , a pre-explosion, before a further explosion in the reactor chamber, which will also be referred to here as the first explosion, initially and essentially occurs or takes place in the feed line} . As a rule, the pre-explosion does not achieve _{complete passivation of the filter condensate with regard to the amount of filter condensate introduced into the feed line. However, a substantial conversion of a relevant portion of this amount is} achieved by the pre-explosion in the sense of passivation. Due to the pre-explosion, if the feed line _{and the reactor chamber are not separated from each other, as is preferred, the filter condensate is also driven further into the reactor chamber. The pre-explosion can also trigger a further explosion in the reactor} chamber. This further explosion is also referred to below as the first explosion. The pre-explosion is, so to speak, an initial explosion in the feed line. Since the required stoichiometric ratio is generally not achieved in the feed line, complete conversion cannot generally be achieved by the pre-explosion for this reason alone. _{[0022] The pre-explosion preferably only takes place or is preferably} only triggered when new filter condensate, i.e. a new first quantity of filter condensate, is introduced into the feed line. The pre-explosion and the first explosion in the reactor chamber can occur immediately one after the other, possibly separated by only fractions of a second.

31257N1PCT – 31.10.2024 _{[0023] The pre-explosion can cause the ignition for the first explosion.} The pre-explosion can also cause a distribution of particles of the filter condensate in the reactor chamber, in particular in the atmosphere of the reactor chamber, which is typically provided by air, which is advantageous for the first explosion. _{[0024] Accordingly, in such a process, the feed line is} preferably included in the passivation process. In particular, by triggering the described pre-explosion in the feed line and subsequently _{carrying out the first and optionally second, third, etc. explosion in the reactor chamber, a favorable passivation can} be achieved. _{[0025] In the pre-explosion, it is further preferred, as already stated, that the feed line is not separated from the reactor chamber. Even if the} pre-explosion essentially takes place in the feed line, the entire volume consisting of the feed line and the reactor chamber is nevertheless enclosed. _{[0026] In detail, the procedure can be such that after cleaning the filter device, a shut-off valve} is _{closed upstream of the feed line, usually and preferably also upstream of a transport device for filter condensate, which can be designed as a rotary valve,} for example, and a shut-off valve downstream of the reactor chamber, the space thus interconnected from the feed line and the reactor chamber _{is evacuated. For example, down to a pressure of 200 millibars, preferably} 150 or less millibars, up to about 50 millibars, more preferably at about 100 millibars.

31257N1PCT – 31.10.2024 _{[0027] The shut-off valve is then opened in the flow direction upstream of the transport device, i.e. in particular the rotary valve, whereby} the filter condensate _{enters the transport device, preferably the rotary valve. A shut-off valve downstream of the transport device but upstream of the} feed line has preferably also been closed beforehand. _{[0028] With the aid of the transport device, the filter condensate is portioned with a view} to a subsequent explosion in such a way that, with _{regard to the volume of the feed line and/or the reactor chamber, a} required ratio to the oxygen then supplied, in particular as a _{proportion of air, is achieved. This is adjusted to the required stoichiometric ratio. Alternatively, the supplied oxygen (air) can also be determined taking into account} the amount of filter condensate introduced. _{[0029] In a further step, the shut-off valve upstream of the transport device is closed and the shut-off valve downstream of the transport device is opened} . The transport device is then activated, causing the filter condensate to be passivated to enter the feed line. Both gravity and, in the sense of and/or, a pressure difference between the transport device and the previously evacuated feed line together with the reactor chamber can be effective. _{[0030] With regard to the pre-explosion, the filter condensate introduced into the feed line is preferably subjected to a pressure surge, preferably based on} ambient air. However, a pressure surge can also be applied with pure oxygen or with air with a higher oxygen content. 31257N1PCT – 31.10.2024 _{[0031] This pressure surge can initially cause the filter condensate in the} supply line to be swirled. This can _{further result in friction between the individual particles of the filter condensate, particularly as a result of the swirling, or in friction between} the particles on the wall of the supply line or with the supplied medium, thereby resulting in ignition of the filter condensate. In any case, the pre-explosion already _{achieves significant passivation. The pre-explosion and a first explosion possibly caused thereby can already achieve very extensive passivation, which may even be sufficient depending on the composition} and/or quantity of the filter condensate _{. In particular, it is preferred that the energy required for such an explosion, particularly a pre-explosion, with regard to} ignition is generated only by the frictional power resulting from the swirling. _{[0032] The ignition and triggering of a pre-explosion in the supply line} can be achieved particularly well if, as preferably provided within the scope of the disclosure given here, raw powder, i.e., unused additive material, _{is previously deposited, preferably upstream of the filter device from which the filter condensate originates. Alternatively} or additionally, the ignition and triggering of the pre-explosion in the supply line can be achieved by injecting the second quantity, usually air, with a high pulse. This pulse can be influenced by the pressure under which the second quantity is, as well as by the geometry of the inlet opening and/or the geometry of the supply line. _{[0033] Furthermore, the pressure surge or otherwise injected medium, in particular ambient air, is preferably used} to induce the 31257N1PCT – 31.10.2024 Filter condensate, optionally after the pre-explosion, is conveyed from the supply line into the reactor chamber. _{[0034] The quantity of compressed air supplied for the preferably carried out pressure surge, preferably supplied from a pressure accumulator, can have a volume} of, for example, 10 to 15, preferably about 12 to 14, more preferably 13 liters. The pressure level in the pressure accumulator can be significantly above ambient pressure, approximately between 3 and 7, more preferably between 5 and 6 bar. _{[0035] In further detail, with regard to the negative pressure (vacuum) previously generated in the supply line or the negative pressure generated including the reactor} chamber, the quantity of medium (air) supplied is selected such that after the medium has been supplied to the extent mentioned, a pressure of about 950 millibars, _{but also up to about 1300 mbar, is established in the supply line and the reactor chamber. [0036] In further detail, if corresponding data is acquired by sensors, it can} be calculated and ultimately determined via a control device that only or essentially the same amount of compressed air or general medium is injected so that approximately the stated pressure _{of 950 millibars or a different, in particular a higher, selected pressure is achieved. [0037] Although the injection of compressed air into the supply line in} the manner described generally achieves a self-ignition of the filter condensate, it is also provided in a further development _{that, in addition to or alternatively to the injection, an ignition spark is generated in the} supply line or in the reactor chamber to trigger, in particular, 31257N1PCT – 31.10.2024 the pre-explosion or the first explosion. Several ignition sparks can also be generated, in particular both in the supply line and in the reactor chamber. _{[0038] After ignition and the resulting pre-explosion and/or first and optionally subsequent second etc. explosion, a waiting period is preferably provided. For example, from 20 to 40, preferably about 30 seconds after the explosion or, if compressed air is injected,} after the injection of the compressed air has been completed. Thereafter, the supply line, including the reactor chamber, is _{preferably (re)evacuated using a vacuum pump. The said waiting time is based} on empirical values that have been observed regarding a period of time _{required until suspended parts have essentially} settled again. Depending on the material processed in additive manufacturing, different periods of time can occur here. _{[0039] The evacuated medium is further preferably passed through a separate} extraction filter. In the extraction filter, particles—in this case, these are passivated particles, which are generally present after the explosion, particularly suspended in the supply line and/or the reactor chamber—are separated on the extraction filter. The particles thus separated may also contain particles extracted during the evacuation that had previously settled on the walls or floor. The medium thus purified can, for example, be discharged into the environment of the system, since it is purified. This can also be done, for example, via the exhaust air of the vacuum pump provided for this purpose. 31257N1PCT – 31.10.2024 _{[0040] Alternatively or additionally, the exhaust air can also be discharged via an exhaust air device of the additive manufacturing system itself. [0041] The extraction filter itself is also preferably cleaned, for example as a function of a} predetermined pressure drop occurring at the filter. This can be done in particular by a gas pressure surge, more preferably a protective gas pressure surge. In this case, the filtrate, which is essentially blasted off by the extraction filter, is conveyed into the feed line from the reactor chamber to the collecting vessel and thus ultimately into the collecting vessel. _{[0042] In a first embodiment of the method, an explosion, in the sense of a first explosion, is immediately triggered in the reactor chamber. In this case, no (pre-)explosion has been triggered beforehand. With such a} method, the feed line can also be comparatively short, or even non-existent. The filter condensate can be fed directly into the reactor chamber, and the second amount of oxidant can also be added to the reactor chamber immediately. _{[0043] The following description can also refer to a first explosion in the reactor chamber, which (only) unfolds after a pre-explosion in the feed line} . _{[0044] In the embodiment of the method, in particular also the method without a pre-explosion, it is preferably provided that the passivation} is carried out _{several times by inducing the first explosion with respect to the same first amount} . This first explosion, which is then _{followed by the corresponding second and optionally third explosion, etc., is carried out in the reactor-} 31257N1PCT – 31.10.2024 _{chamber. It may occasionally happen that the first controlled explosion carried out} has not yet led to complete or sufficient passivation of the first quantity. In this case, the same first quantity can be detonated again, wherein a further quantity of oxidizing agent, i.e. a third, fourth, etc. quantity of oxidizing agent, can be introduced into the reactor chamber for a further explosion. The further quantity of oxidizing agent can preferably be introduced directly into the reactor chamber, preferably also via a corresponding line opening into the reactor chamber. _{[0045] Preferably, the reactor chamber is also designed with a measuring device, at} least for a temperature and/or a pressure in the reactor chamber. The temperature in the reactor chamber is preferably measured during the _{implementation of the first explosion, in particular the first explosion, possibly also following a pre-explosion, the second explosion, etc. Likewise,} the pressure in the reactor chamber is preferably _{measured alternatively or additionally during the implementation of the explosion. Based on the resulting} temperature and/or pressure, it can be evaluated _{whether or not sufficient passivation is present. Using the measured} pressure, in particular measured pressure peaks, _{the number of explosions can also be counted simultaneously. Furthermore, however, an oxygen content in the reactor chamber can also} be measured alternatively or additionally. _{[0046] In particular, it is preferred that the passivation is repeated by causing the first and second explosions, in particular, triggered in the reactor chamber, for as long as a predetermined temperature and/or pressure is exceeded and/or the oxygen content falls below a predetermined value.} 31257N1PCT – 31.10.2024 _{is measured during the explosion. As long as the first batch still contains a significant proportion of non} -passivated filter condensate, _{the temperature and/or pressure will exceed a predetermined value during an explosion} , causing the oxygen content to drop. With regard to the oxygen content, it may be advisable to monitor whether the oxygen content falls below a predetermined value. If this oxygen content is not undercut, this alone or in combination with one of the other values can _{indicate that the desired passivation has been achieved. When an explosion is triggered for the first time,} a drop in the oxygen content is an important indicator of successful passivation of the first batch. If the same first batch is detonated several times in succession, the lack of a drop in oxygen is an indication that _{sufficient passivation was already achieved in the previous explosion. If the} passivation has been completed to a significant, or at least sufficient, extent, the specified temperature and/or pressure is no _{longer reached and/or a specified oxygen content is not undercut, so that this can be used as a trigger for considering the passivation} complete and transferring the passivated filter condensate from the reactor chamber to the collection chamber. _{[0047] The specified temperature and/or pressure, and possibly also a considered oxygen content, can vary depending on the specific additive} manufacturing process in which the reactor device is integrated. It can be determined empirically accordingly. _{[0048] The filter condensate in a conventional additive manufacturing system} can _{contain unused additive manufacturing material, the so-called raw powder, which may also be recyclable. It} 31257N1PCT – 10/31/2024 Within the scope of the disclosure given here, it is preferred to separate _{raw powder and unused} additive material from the filter _{condensate before it is introduced into the reactor chamber, more preferably before it} is separated with particles transported out of the process chamber for additive manufacturing with process gas in the filter device _{. This is particularly in the interest} of better predictability or determinability of the required stoichiometric ratio between filter condensate and oxygen _{. Several possibilities exist for this. One simple possibility} is _{to first pass a quantity of gas carried out of a process chamber in which additive manufacturing takes place, which carries the raw powder,} through a separator, such as a cyclone separator or impact separator, before the filter device. _{The raw powder and any spatter can be advantageously separated in the separator} . _The separation can particularly take advantage of the fact that these components are usually relatively large particles, approximately larger than _{10 µm. The particles ultimately separated in the filter condensate} have sizes that are essentially in the nano range. The particle sizes of the particles that can be separated in the separator are _{generally in a range between 10 and 70 µm. This allows} the proportion of reactive filter condensate to be increased or _{kept at a predictable proportion, so that the stoichiometric adjustment} can be carried out more reliably. _{[0049] The amount of filter condensate that is passivated in the manner described} can vary. In an initial design _{, a quantity between 5 and 25 ml is preferably used. However, by selecting the appropriate} size of the reactor chamber, optionally combined with the size or _{volume of the feed line, this amount can be varied within wide limits} . 31257N1PCT – 31.10.2024 _{[0050] The second quantity, the oxidizing agent, is preferably air and more} preferably ambient air. In principle, oxygen can also be used in a higher proportion or even pure oxygen. _{[0051] It is further preferred that in a case where the triggering of the explosion, in particular the first explosion, is not already initiated by the stirring up itself,} the triggering of the explosion is carried out. The stirring up is _{preferably, as already explained, also carried out by the introduction, preferably injection , of the second quantity, the oxidizing agent, i.e. preferably by the introduction of air. The stirring up is carried out in such a way} that _{an explosive dust cloud results in the feed line and/or the reactor chamber. If the explosion is not carried out immediately with} the stirring up, but with a certain time interval after the initiated stirring up, the advantage can be that a better distribution of the filter condensate in the second quantity and thus _{also in the reactor chamber can be achieved, so that the success of the explosion is possibly greater.} The aim is to achieve _{the most homogeneous distribution possible of a dust cloud generated by the} filter condensate in the reactor chamber. _{[0052] In one embodiment, the explosion can be achieved by applying a} pressure surge already described in the supply line (as a pre-explosion) _{and/or the reactor chamber, by swirling, preferably with a} comparatively strong, also known as a hard-response, gas jet, in particular an air jet. With regard to the first and optionally second _{and further explosion (in the reactor chamber), one embodiment provides that the explosion is triggered by an ignition device, such as an ignition device generating an ignition spark. The ignition spark} can, for example, be generated by a spark plug or a device corresponding to a spark plug. 31257N1PCT – 31.10.2024 _{appropriate device. The ignition device can also, if necessary only, be designed to form a flame. According to a further} version, as an alternative to ignition via an ignition device, it is provided that even if only the first and possibly _{further explosions are triggered as an explosion in the reactor chamber, this - first and further - explosion is also triggered by the turbulence as described for the supply line} , by supplying the second quantity, in particular here also preferably with a relatively high pressure surge, for example. _{[0053] In addition or alternatively, it is also preferred that the ignition spark or} several ignition sparks _{are activated one after the other over a longer period of time. This also has a favorable effect on the exploitation, in particular of the first and possibly second and further explosions . If necessary, several ignitions (explosions) can be} achieved in succession without having to run through a completely new cycle, i.e., in particular, without _{having to resuspend and/or inject a second amount. For this purpose, the voltage generating the ignition spark is preferably} designed to be comparatively high, _{preferably in the range of 3 to 7.5 kV. Even if the mixture is at a} lower explosion limit, reliable ignition and thus explosion can be achieved. The voltage at which the ignition spark is generated preferably corresponds to a multiple of the minimum ignition energy of the condensate. _{[0054] Notwithstanding the fact that the triggering of the explosion via the ignition} device is preferably carried out with respect to the first explosion in the reactor chamber, the triggering of the pre-explosion can also be carried out by an ignition device. 31257N1PCT – 31.10.2024 [0055] The period of time can _{be varied and determined depending on the pressure, temperature and/or oxygen content measured during a previously conducted} explosion. If the pressure during a previous explosion is comparatively low, the ignition spark or sparks are preferably triggered over a longer period of time. _{[0056] The feed line and/or the reactor chamber can be substantially} cylindrical, correspondingly having a cylindrical length and a cylindrical diameter. In this case, the reactor chamber can more preferably have a length to diameter ratio of 4 or less _{. In particular, the feed line, if used for a pre-explosion} , and the reactor chamber are preferably matched to the amount of filter condensate so that the most ideal _{condensate or dust-air mixture possible can result during the resuspension. [0057] The reactor chamber is preferably comparatively compact . A possible design for the reactor chamber is therefore also a spherical chamber. [0058] The ignition device is preferably arranged in a lower region of the reactor} chamber, for example, in a lower third of the reactor chamber. This is in view of the effect of gravity. The lower third can be determined accordingly along a longitudinal axis, i.e., one-third of the longitudinal axis or less, of the reactor chamber, even in the case of a spherical configuration. _{[0059] With regard to the value ranges specified above and below, such as a volume value range of, for example, 10 to 15 l, all intermediate values, in particular in tenths, i.e., 10.1 l to 15 l, 10 l to} 31257N1PCT – 31.10.2024 _{14.9 l, 10.2 l to 15 l, etc. The same also applies, for example, to a} value range as is specified in terms of milliliters; the _{amount between 5 and 25 ml can also be 5.1 to 25 ml, 5 to 24.9 ml, 5.2 to 25 ml, etc.} Brief description of the drawings _{[0060] The invention is further explained below with reference to the attached drawing, which shows exemplary embodiments. Herein: Fig. 1 shows a system with a filter device, a portioning device and a reactor device of a first embodiment} ; _{Fig. 2 shows the portioning device according to Fig. 1 in a longitudinal section} through the plane II in Fig. 1; _{Fig. 3 shows a longitudinal section along the line III in Fig. 2; Fig. 4 shows a longitudinal section according to plane IV of the reactor device shown in Fig. 1} ; Fig _{. Fig. 5 shows a longitudinal section along line V in Fig. 4; Fig. 6 shows the reactor device according to Fig. 5 with a second rotational} position of the shaft; _{Fig. 7 shows the reactor device according to Fig. 6 with a subsequent} rotational position of the shaft; 31257N1PCT – 31.10.2024 _{Fig. 8 shows a further embodiment of a reactor device, in particular a shaft of the reactor chamber; Fig. 9 shows a section along the line IX in Fig. 8; Fig. 10 shows the reactor device according to Fig. 9 with the shaft in a} second position; _{Fig. 11 shows the reactor device according to Fig. 10 with the shaft in a} third rotational position; _{Fig. 12 shows the reactor device with an expansion chamber; and Fig. 13 shows the system with a filter device, a portioning} device and a reactor device according to a second embodiment. Description of the Embodiments _{[0061] Figure 1 shows a merely exemplary system as a subsystem comprising a} manufacturing facility for additive manufacturing with a filter device 2, a portioning device 7, and a reactor device 1. The filter device is connected, for example, downstream of a metal printing device (not shown) in order to filter contaminated process gas during a metal printing process and _{to passivate the filter condensate 3 collected within the filter device 2 by means of the reactor device 1, so that the chemical reactivity} of the filter condensate 3 is no longer sufficient _{to ignite upon contact with oxygen or to ignite fire-prone objects.} 31257N1PCT – 10/31/2024 _{[0062] The system shown can also be used for other industrial facilities in which reactive filter condensate is produced, instead of in connection with metal} printing devices. The exemplary structure shown below, in particular of the reactor device 1 and also of the portioning device 7, remains unaffected. _{[0063] During additive manufacturing, such as a metal} printing process, process gas that has flowed through a _{process chamber in which the metal printing or additive manufacturing} takes place, is preferably regenerated. For this purpose, the process gas, for example a protective gas such as argon or nitrogen, is blown into the process chamber and extracted again. The gas circuit can be achieved, for example, by a pump or a blower designed as a side channel compressor. The extracted process gas is filtered within the filter device 2 and freed from pollutants, which subsequently form, among other things, the filter condensate 3. _{[0064] The filter condensate may, under certain circumstances and to a considerable extent,} at least in previously known process configurations, which are also generally usable in the present case, still contain raw powder to be used for additive manufacturing and, for example, spatter. In this context, according to the system described here, it is advantageous to provide a separation device with which raw powder is removed from the filter condensate before it is introduced into the reactor chamber. This can _{further facilitate passivation. Preferably, the separation is also carried out upstream of the filter device in the process sequence} . [0065] For this purpose, according to one possible embodiment, a separation device, such as a cyclone _{separator 43 in the illustrated embodiment, can be connected upstream of the filter device 2.} 31257N1PCT – 10/31/2024 _{The separation device is configured such that material not used in additive manufacturing , raw powder, and possibly also spatter, is separated from} the filter condensate and, preferably, at least with regard to the raw powder, _{is made available again to the additive manufacturing process. The separation device can be designed in different ways.} With a cyclone separator, a weight difference between unused (unreacted) starting material and the _{used filter condensate ultimately fed to the collection chamber can be utilized. The separator can also be an impact separator. [0066] With regard to a method for cleaning a filter of the filter} device 2 as well as the filter device 2 itself, reference is _{made to DE 102019132349 A1 (US 2022/0362691 A1) merely by way of example. The} content of this document is hereby incorporated in its entirety into the disclosure of the present invention, also for the purpose of incorporating features of this patent application into claims of the present invention. _{[0067] To clean the filter of the filter device 2 and to remove} the filter condensate 3 that settles on the filter during filtration of the process gas, the filter device 2 can be put into regeneration mode. For this purpose, the filter device 2 can first be removed from a flow of process gas and cleaned, for example, via a separate pump or a side channel compressor, which generates negative pressure within the filter device 2. Alternatively or additionally, a pressure surge, in particular with an _{inert gas, can be generated for cleaning, which is directed opposite to the flow during filter} operation. After reaching a defined pressure drop across a filter wall, as an indicator for the required cleaning, 31257N1PCT – 31.10.2024 For _{example, a flushing medium can be directed onto the filter wall in order to flow through the filter} wall in a flow direction opposite to that of a filtering process. For a detailed explanation of a possible embodiment of the filtering process and regeneration process of such a filter device _{2, reference is made, for example, to the document DE 102021116264 A (also} published as WO 2022/268497 A1). The content of this document _{is hereby fully incorporated into the disclosure of the present invention} , also for the purpose of incorporating features disclosed therein into claims of the present invention. _{[0068] The filter device 2, optionally following the separation device, is connected to the reactor device 1 or the portioning device 7 by means of a gas-tight, in particular air-tight, valve 32, here, for example} , a disk valve. Downstream of a transport device, here the _{portioning device 7, i.e. between the portioning device 7} and the reactor device 1, there is a further valve 33, which here _{is also preferably designed as a disk valve. Furthermore, such a valve can} also be arranged downstream of the filter device but upstream of the separation device. During filter cleaning, the filter condensate 3 is conveyed through the open valve 32 into the portioning device 7. The valve 32 is then closed and the reactor device 1 is evacuated with the valve 33 open down to the blocked valve 32. _{The portioning device 7 is then actuated so that the filter condensate 3} is transported _{into the reactor device 1 according to a first possible process configuration . Within the reactor facility 1, the filter condensate 3 is} then _{treated as part of a passivation process, in this case the targeted triggering of an explosion, until its chemical reactivity has fallen below} a previously defined reference value or reference range and 31257N1PCT – 31.10.2024 no longer poses a fire hazard. Before carrying out the passivation process, the valve 33 is closed and preferably ambient air is introduced into the reactor device 1 as an oxidizing agent. _{[0069] After the passivation process is completed, a further valve 34 located behind the reactor device 1 is} opened in order to convey the passivated filter condensate 3 from the reactor device 1 into a collection chamber 9. Between the reactor device 1 and the collection chamber 9, there is a further valve 35 behind the valve 34. This valve 35 can be closed if the collection chamber 9 is to be removed from the system. The valve 35 thus serves as an additional safety device. In principle, however, this valve 35 can be dispensed with since the preceding valve _{34 is already sufficient as protection against the ingress of air into the reactor device 1. [0070] With reference to Figures 2 and 3, a possible embodiment of the transport device, here specifically the portioning device 7, which is arranged upstream of the reactor device 1, is first} explained. The portioning device 7 is designed here merely as an example as a rotary valve. The portioning device 7 accordingly has a rotary valve housing 27 and a rotary valve 28 rotatably mounted in the rotary valve housing 27. The rotary valve 28 preferably has a plurality of rotary valve chambers 31, for example two, three, four or more rotary valve _{chambers 31, which are arranged one behind the other in the direction of rotation of the rotary valve 28.} The rotary valve 28 has two opposite end faces 29, one of which is supported against the rotary valve housing 27 and the other preferably against a disk 30. The disc 30 is preferably acted upon by the restoring force of a spring element 36, which is arranged in relation to a roller 31257N1PCT – 31.10.2024 tation axis 37 of the cellular wheel 28 acts in an axial direction and thus presses the disc 30 against the adjacent end face 29 of the cellular wheel 28. The force-locking connection acting in the axial direction of the rotation axis 37 of the cellular wheel 28 between the disc 30 and the cellular wheel 28 and also between the cellular wheel 28 and an adjacent housing wall of the cellular wheel housing 27 ensures that filter condensate 3 cannot _{escape from the cellular wheel chambers 31 of the cellular wheel lock into the environment. In addition,} the position of the disc 30 is shifted or adjusted if material wear occurs due to friction of the cellular wheel 28 on the disc 30. The spring element 36 thus automatically adjusts the position of the disk 30, whereby the spring force of the spring element 36 still allows rotation of the cellular wheel 28 relative to the cellular wheel housing 27 on the one hand and the disk 30 on the other hand. _{[0071] Although this is not shown here, a lock consisting of two valves and a space arranged between them can also be used as the portioning} device 7 instead of the illustrated cellular wheel lock. The space between the valves determines the amount of filter condensate 3 portioned out by the portioning device 7 per portion stroke. Furthermore, other embodiments of portioning _{devices 7 are also conceivable, which can be used in conjunction with the reactor} device 1. The functioning of the reactor device 1 is not affected by this. _{[0072] In the portioning device 7, which is designed as a rotary valve in Figures 2 and 3, a portion of a total amount of filter condensate 3 located in the filter device 2 is first} taken up into a first rotary chamber 31 of the rotary chamber 28. For this purpose, the valve 31257N1PCT – 31.10.2024 Valve 32, which is arranged between the filter device 2 and the portioning device 7, is opened so that the filter condensate 3 can fall through the open valve 32 into the rotary valve. The valve 32 is then closed and the portioning device 7 is evacuated. The evacuation of the portioning device 7 preferably takes place simultaneously with the _{evacuation of the further downstream feed line 44 and the reactor device} 1 with _{the valve 33 located between the portioning device 7 and the reactor device 1 open. After evacuation, the rotary valve 28 of the portioning device 7 is} rotated about the rotation axis 37, whereby the filter condensate 3 stored in one or more rotary valve chambers 31 is transported into the reactor chamber 5 of the reactor device 1. If swirling is provided, a nozzle for introducing a swirling gas, in particular air, into the reactor chamber can be provided for this purpose. _{[0073] Alternatively, the filter condensate can also be introduced into the reactor chamber by injection, for example by means of an inert gas or air as already mentioned. This can optionally simultaneously stir up the flow} and, in the case of air, also introduce oxygen. _{[0074] As can be seen in particular from Figure 3, in the case of the rotary valve, the rotary wheel 28 here has, for example, only two rotary wheel chambers 31} , which are opposite one another with respect to the rotation axis 37. While a first rotary wheel chamber 31, upper with respect to the orientation shown in Figure 3, is filled with filter condensate 3, the opposite, lower rotary wheel chamber 31 is emptied in the direction of the reactor device 1. _{[0075] As can also be seen, the portioning device 7 is preferably} set so that the cell wheel 28 is in a starting position in which 31257N1PCT – 31.10.2024 one of the cell wheel chambers 31 is filled, is slightly inclined so that a chamber bottom of the cell wheel chamber 31 is not oriented horizontally. This can help to ensure that when the cell wheel 28 rotates by 180 degrees, the cell wheel chamber 31 is completely emptied and _{that no parts of the filter condensate 3 remain in the portioning device 7.} If, moreover, partial quantities of filter condensate 3 are located in a clearance between the cell wheel 28 and the cell wheel housing 27, _{these can be released by over-rotating by more than 180 degrees} . It is also possible to support the transport of the filter condensate 3 with a gas stream. According to a further possibility, the valve 32 could also be opened first and the valve 33 closed first. Then, only the reactor device 1 could be evacuated, without simultaneously evacuating the portioning device 7. Upon actuation of the rotary valve, the filter condensate 3 would then fall onto the closed valve 33 and, after the valve 33 is opened, be sucked into the reactor device 1 until pressure equalization occurs between the filter device 2 and the reactor device 1. _{[0076] In all described embodiments, the bearing points of the portioning device 7 can} be flushed with a protective gas after the filter condensate 3 has been discharged into the reactor device 1. This cleans the bearing points, and any filter condensate 3 that could not reach the reactor device 1 is transported into the reactor device 1. _{[0077] After the filter condensate 3 has left the portioning device 7 and also the feed line 44, it enters the reactor device} 1. As can be seen in particular from Figure 1, the reactor device 1 has a filter-side filter device connection 6, via which the filter 31257N1PCT – 31.10.2024 condensate 3 can flow into the reactor device 1. At a lower end region opposite the filter device connection 6, the reactor _{device 1 has a collection chamber connection 8 in a similar manner} , which is connected to the collection chamber 9, which ultimately collects the passivated filter condensate 3. The collection chamber 9 can be separated from the reactor device 1 in order to be able to dispose of the filter condensate 3 contained therein. The reactor device 1 further has an extension chamber 23 (see Figures 1 and 12), the function of which will be described in more detail later. The extension chamber 23 has a closure 38, here for _{example in the form of a flange. [0078] With reference to Figures 4 to 7, a first embodiment of a possible reactor device 1 is first} described. _{[0079] The reactor device 1 has a reactor housing 4 in which} a reactor chamber 5 is formed. With a view to an explosion-proof design of the reactor chamber 5, the wall or the _{housing is designed such that it can withstand increased pressures, in particular up to 2 bar or more, for example 8 bar, 10 bar or up to 15 bar or more. [0080] For example, a rotatable shaft 10 is mounted on the reactor housing 4, which penetrates the reactor chamber 5 and, based on the rotational position of the shaft 10 shown in} Figures 4 and 5, contacts a partial area of the reactor housing 4, so that the reactor chamber 5 is divided by the shaft 10 into a reaction chamber 11 and a discharge chamber 12. A portion of the circumferential surface 14 of the shaft 10 forms a reactor base 40 for the reaction chamber 11. 31257N1PCT – 31.10.2024 _{[0081] As an alternative to a rotatable shaft 10, a division of the reactor space 5 into a reaction chamber 11 and a discharge chamber 12 could} also be achieved by other structural measures, for example by a flap forming the reactor bottom 40 of the reaction chamber 11 or a sliding housing section of the reactor housing 4. _{[0082] In order to achieve contact between the circumferential surface 14 and the inner} wall of the reactor housing 4, the shaft 10 has, for example, different sized outer diameters in its longitudinal extent, i.e. parallel to its axis of rotation 18. A circumferential section 13 with a largest diameter can be sealed from the reactor housing 4 by a bushing 16. The bushing 16 can be pressed onto the circumferential surface 14 of the shaft 10 by a spring element 39. This creates a connection to the reactor housing 4, which simultaneously also separates the reaction chamber 11 and the discharge chamber 12 of the reactor _{space 5. [0083] The bushing 16 can be designed as a cylindrical hollow body whose longitudinal axis} 17 is orthogonal to the rotational axis 18 of the shaft 10. _{[0084] The circumferential portion 13 of the shaft 10 projecting into the reaction chamber 11} has a receiving area 15 for filter condensate 3 introduced into the reactor device 1. The receiving area 15 is, for example, a concave material recess here. _{[0085] As can be seen in particular from Figures 5 to 7, a total of four such receiving areas are preferably} provided over the circumferential surface 14 of the shaft 10. 31257N1PCT – 31.10.2024 Measuring areas 15 for the filter condensate 3 are formed. Two receiving areas 15 can be located opposite each other with respect to the rotation axis 18 of the shaft 10. By each 90-degree rotation about the rotation axis 18 of the shaft 10, a different receiving area 15 of a different circumferential partial area 13 of the shaft 10 can always be displaced into the reaction chamber 11. The respective circumferential partial area 13, together with the inner wall _{of the bushing 16 and the remaining inner wall of the reactor housing 4, forms the reaction} chamber 11. At least one connection 26 can open into the reaction chamber 11, here for example two connections 26, via which oxidizing agent can be introduced into the reaction chamber 11. The oxidizing agent here is oxygen or oxygen-containing ambient air. _{[0086] As can also be seen from Figures 5 to 7, the reaction chamber 11 can} further comprise at least one temperature sensor 24 and/or at least one pressure sensor 25, which are configured via an evaluation device of the reactor device 1, for example a computer processor, so that a temperature or a pressure within the reaction _{chamber 11 can be measured. Furthermore, alternatively or additionally,} a gas sensor for measuring an O2 content can also be provided. With one, several, or all of these measured values, _{one or more explosion processes of the passivation process of filter condensate 3 within the reactor device 1 can be monitored—as will also} be explained below. [0087] The reaction chamber 11 can _{be expanded with respect to the jacketed gas volume by means of the expansion chamber 23 shown in Figure 1} . _{[0088] The operation of the reactor device 1 according to this first embodiment} (Figures 4 to 7) is now described below. 31257N1PCT – 31.10.2024 _{[0089] When the shaft 10 is in the initial position shown, for example, in Figure 4} , the filter condensate 3 from the portioning device 7 passes via the feed line 44 into the reaction chamber 11, which _{is spatially separated from the discharge chamber 12 or at least a subsequent line section by the form-fitting and force-fitting engagement of the bushing 16 with the circumferential portion 13 of the shaft 10. The} spatial separation ensures that the filter condensate 3 remains only in the reaction chamber 11 of the reactor space 5 as long as it has not yet been passivated. As soon as the filter condensate 3 has collected in the concave receiving area 15 of the circumferential surface 14 of the shaft 10 due to the effect of gravity, the valve 33 located between the reactor device 1 and the portioning device 7 is closed. Subsequently, the reaction chamber 11 can preferably be evacuated together with the tubular expansion chamber 23 until a predefined pressure is reached. Air can then _{be introduced into the reaction chamber 11 as an oxidizing agent via the connections 26 from the immediate external environment of the reactor device 1. The connections 26 here are, for example, small bores} or valves in the bushing 16, which _{are oriented obliquely to the longitudinal axis 17 of the bushing 16, so that the inflowing ambient air preferably} hits the receiving area 15 of the shaft 10 directly and essentially in a straight line. However, the air or the oxidizing agent can also be introduced, for example, by injection, without or without significant evacuation. As a result, the filter condensate 3 collected in the receiving area 15 is _{swirled within the reaction chamber 11 and optionally within the expansion chamber 23 and transported upwards, i.e., optionally in the direction of the expansion chamber 23. As soon as a} predefined pressure or the ambient pressure within the reaction chamber 11 or within the expansion chamber 23 is reached (which can be measured by means of the pressure sensor 25), the supply of oxidant 31257N1PCT – 31.10.2024 _{stopped by the connections 26. An explosion is then triggered,} as described in more detail below. _{[0090] The passivation cycle described above can be repeated} until the filter condensate 3 _{has reached a predefined desired passivation state. The passivation state can be determined by measuring a temperature, a pressure and/or an oxygen content within the reaction chamber 11 or the expansion chamber 23. For this purpose, a temperature, pressure and/or oxygen measurement is carried out during passivation} . The temperature and/or the pressure are preferably also _{measured continuously during the explosion. If the temperature and/or the} pressure and/or an oxygen content _{rises above a specified reference value or reference range or has not yet fallen} (oxygen), it can be concluded that the filter condensate 3 is not yet sufficiently passivated, ie still has a residual chemical reactivity _{that poses a fire hazard. Therefore, the explosion passivation cycle is} carried out once more by bringing the same portion of _{filter condensate 3 located in the reaction chamber 11 into contact with the oxidizing agent again} . As soon as the temperature and/or pressure _{no longer increases, or at least no longer increases significantly, and/or the oxygen} content does not reach a predetermined value, in particular _{no longer exceeds a predetermined temperature and/or a predetermined pressure and/or falls below a predetermined oxygen content, the filter condensate 3 has} reached a thus-defined safe passivation state. The passivated filter condensate 3 can then be transferred from the reaction chamber 11 to the discharge chamber 12 of the reactor device 1. _{[0091] Alternatively, to ensure complete passivation of the filter condensate 3, it is} possible to add a required amount of oxidizing agent 31257N1PCT – 31.10.2024 _{to fully passivate the first quantity, the filter condensate 3, in advance and then to calculate a number of passivation cycles, i.e. required explosions, which is necessary to passivate the total} quantity of filter condensate 3 over several consecutive passivation cycles. _{[0092] The reaction, i.e. the explosion, which can be the pre-explosion} as well as the first and possibly second etc. explosion, can optionally be assisted by heating the oxidizing agent before it flows into the reaction chamber 11. This can stimulate a reaction of the filter condensate 3, so that the passivation is started early and/or is completed more quickly. The heating of the oxidizing agent can take place, for example, with the aid of heating elements which heat a wall of a reaction chamber feed line. Preferably, for example, it is also possible _{to design a wall of a reaction chamber feed line as a heat exchanger (heat transferor), e.g. by passing a warm liquid} through a cavity in the wall. Alternatively, it is also possible to heat the oxidizing agent in a separate vessel or space outside the feed lines of the reactor device. _{[0093] As soon as the desired passivation state of the filter condensate 3 is reached and the filter condensate 3 has collected at the intended position,} namely the receiving area 15 of the shaft 10, the _{shaft 10 is rotated, in the illustrated embodiment, by 90 degrees about the rotation axis 18. In doing so, first (among others) the intermediate position shown in Figure 6 is} reached, in which the reaction chamber 11 has a flow connection to the discharge chamber 12 of the reactor space 5. The filter con- 31257N1PCT – 31.10.2024 collected in the receiving area 15 of the shaft 10 Densate 3 can _{leave the reaction chamber 11 via the gap created between the shaft 10 and the bushing 16} and finally - as _{shown in Figure 7 - migrate in the direction of the collection chamber connection 8, which} establishes _{the connection to the collection chamber 9 when the valves 34 and 35 are open} . _{[0094] The receiving area 15 can then be cleaned if necessary} , preferably by blowing inert gas into the reactor chamber 5. The bearings of the shaft 10 can also be cleaned within the reactor chamber 5 in this way. _{[0095] Figures 8 to 12 disclose a further of several other} possible embodiments of a reactor device 1. As can initially be seen with reference to Figure 8, the reactor device 1 in this embodiment also has a reactor chamber 5 with a shaft 10, which can separate a reaction chamber 11 from a discharge chamber 12. Between a circumferential section 13 of the shaft 10 and the reactor housing 4, a bushing 16 is arranged, which _{is pressed onto the circumferential surface 14 of the shaft 10 with the restoring force of a spring element 39. [0096] In contrast to the previously described embodiment (Figures 4} to 7), the shaft 10 in the second embodiment does not have a receiving area 15 designed as a recess for the filter condensate 3, but _{instead has a curvature 21 which - as can be seen, for example, from Figure 8 - continues in the direction of the longitudinal extent of the rotational axis 18 of the shaft 10. As a result, the curved circumferential section 13 of the shaft 10 adjoins} the annular end face of the cylindrical _{bushing 16 not only in the direction of the circumferential curvature of the shaft 10, but also transversely thereto. It is therefore a total ring-shaped recording area 15 around} 31257N1PCT – 31.10.2024 the curvature 21 of the shaft 10, which serves to receive the filter condensate 3. _{[0097] The shaft 10 has, in combination with the curvature 21, a through-} bore 20 which runs through the shaft 10, for example, orthogonal to the _{axis of rotation 18 of the shaft 10, i.e. in the direction of rotation of the shaft 10.} The through-bore 20 is spatially separated from the curvature 21 or from two opposite curvatures 21 with respect to the circumferential surface 14 of the shaft 10. In particular, the design is such, as can be seen from Figure 8, for example, that the through-bore 20 has a longitudinal direction _{which runs orthogonal to the axis of rotation 18 of the shaft 10, the} through-bore 20 opening out on the circumferential surface 14 of the shaft 10 centrally between two opposite circumferential partial regions 13. _{[0098] According to this embodiment, the emptying of the receiving area 15 located on the circumferential surface 14 of the shaft 10} occurs such that the shaft 10 rotates about the rotation axis 18, whereby a front end area of the through-bore 20 is pushed into a front opening of the bushing 16 and thus also into the reaction chamber 11. As a result, the filter condensate 3 located in the receiving area 15 can _{pass through the through-bore 20 from the reaction chamber 11 into the discharge chamber 12.} This is illustrated in Figures 10 and 11. _{[0099] As previously shown with reference to the embodiment of Figures 4 to} 7, the connections 26 for introducing oxidizing agent into the bushing 16 or the reaction chamber 11 are oriented obliquely to the longitudinal axis 17 of the bushing 16, so that the oxidizing agent flow is directed in the direction of the curvature 21 and an air flow can form in the annular circumferential region of the curvature 21, which air flow carries the filter condensate 3 together with the 31257N1PCT – 31.10.2024 Oxidizing agent is swirled in a spiral shape within the reaction chamber 11 and the connected expansion chamber 23. _{[00100] As shown, the expansion chamber 23 is preferably tubular or cylindrical. It preferably represents a dead space, i.e. it can} only be flowed into and out of, but not through. Preferably in a specific arrangement, as can be seen from the figures of the drawing, _{the expansion chamber 23, or the reactor space as a whole, has a considerable height or length L. The extension chamber 23 or the reactor space is preferably arranged vertically in the longitudinal extent, which has a multiple of a given width or diameter d (relative to the interior space). Further preferred} is a ratio of length to width or diameter d _{of 4 or less. Swirled-up filter condensate 3 can be distributed over} the longitudinal extent in the reactor chamber or the expansion chamber 23. Further preferably, the expansion chamber 23 has a diameter perpendicular to its longitudinal extent, or a largest dimension added thereto, that is larger than the _{dimension of the reactor base 40 in the same direction. Preferably, the dimension is approximately two to three times, more preferably five times or less, as large.} During the fluidization process during a passivation process, access _{to the reactor is closed, as is known. Together with the expansion chamber 23, this creates a closed space in which the passivation, i.e., the explosion, takes place. Furthermore, the expansion chamber 23 can} be arranged and provided with an extension such that the fluidized filter condensate 3 flows vertically past the filter device connection 6 during the fluidization process. 31257N1PCT – 10/31/2024 _{[00101] As can be seen in particular from Figure 12, the passivation, i.e. the explosion, in particular the first explosion already described above} , optionally after a pre-explosion in the feed line, and _{then the second and third etc. explosion, is preferably started deliberately, or the} start of the passivation is supported by generating a spark. The spark can be generated in the expansion chamber 23, as shown in Figure 12, but it can also be generated close to the actual reactor chamber. _{[00102] As can be seen from Figure 12, in one possible embodiment, two ignition electrodes 41, 42 are} provided, which in the exemplary embodiment are also preferably attached to the end 38 of the expansion chamber 23, i.e. close to a tube end of the expansion chamber 23, which is preferably tubular in this respect _{. [00103] Alternatively, a conventional spark plug or a piezo spark generator can also be provided} . _{[00104] To carry out passivation, as explained, a controlled explosion is carried out in the reactor chamber 5. For this purpose, the first quantity, the filter condensate 3 introduced into the reactor chamber 5,} is stoichiometrically adjusted to the second quantity such that an explosive mixture is achieved. The adjustment can be _{carried out by weighing the first quantity, the quantity of filter condensate 3, and from this, it can be determined mathematically what proportion of the second quantity, in particular air,} is to be added. _{[00105] Passivation by explosion is preferably carried out several times in succession} . In preparation for each explosion, the fluidization is also carried out. 31257N1PCT – 10/31/2024 _{[00106] In preparation for each explosion, a further, additional, third or further amount of oxidizing agent, as specified above, can} be introduced into the reactor chamber 5. _{[00107] The temperature in the reactor chamber 5 is measured by means of the temperature sensor 24} , preferably continuously or at least at certain time intervals. The measurement is carried out in such a way that a temperature reached during an explosion can be determined. _{[00108] The pressure in the reactor chamber 5 is preferably also measured via the pressure sensor 25, preferably in the same way, continuously} or at certain time intervals. _{[00109] The first explosion is repeated in the reactor chamber 5 with respect to} the first amount introduced, without any part of the amount being transferred to the collection chamber 9 or a further amount _{being introduced into the reactor chamber 5, until a predetermined temperature and/or a predetermined pressure is no longer exceeded during the deliberately triggered explosion} . _{[00110] The amount of filter condensate 3 introduced into the reactor chamber 5 for passivation can, for example, be 5 to 25 ml. However, it can} also deviate significantly from this, in particular be significantly larger. _{[00111] The explosion is preferably triggered at a predetermined} time interval from the start of the turbulence. A complete turbulence should have developed before the _{explosion is triggered. However, the filter condensate 3 should be} 31257N1PCT – 31.10.2024 still in the swirled state. It should not have settled back on the ground, or not to a significant extent, if possible. _{[00112] The explosion is preferably triggered by the ignition electrodes 41, 42 already described, rather than by means of an ignition spark. This ignition spark} can be triggered several times in succession or over a specific period of time. This period of time can be determined, in particular, as a function of a pressure measured during an explosion. _{[00113] With reference to Figure 13, a possible second system with a filter} device, a portioning device, and a reactor device is shown. The system according to Figure 13 is preferably used, in particular, when a pre-explosion is triggered in the feed line 44. _{[00114] With regard to the filter device 2 and the preferably upstream} separation device for raw powder, here in particular the cyclone separator _{43, the same aspects apply as already described above with reference to Figure 1.} Reference is made to this. _{[00115] This also applies equally to the transport device, here the portioning device 7, and the upstream and downstream valves. [00116] It is evident that in this embodiment, the supply line 44 is significantly} longer than in the system according to Figure 1. _{[00117] Associated with the supply line 44, in particular, a pressure accumulator 45 is} provided, which can also be shut off by valves 46, 47. The pressure accumulator 45 can in turn be fed via an upstream container 48. 31257N1PCT – 31.10.2024 _{[00118] It is also important that an exhaust air filter 49 is provided connected to the reactor chamber 5} , which can be pressurized by a separate vacuum device not shown in detail here, in particular a separate vacuum pump. _{[00119] A further, separate collection chamber 50 can also be provided associated with the exhaust air filter 49, which can also be shut off via a valve 51.} A line 52 leads to and from the exhaust air filter 49 to the collection chamber _{50. As an alternative to the collection chamber 50, filtrate falling out of the exhaust air filter 49 could, in countercurrent operation, as also described above,} be conveyed back into the reactor chamber 5 via the line 53, which establishes the connection to the reactor chamber 5, and then _{conveyed into the collection chamber 9 in the manner also described above. [00120] When carrying out the process with a pre-explosion in the feed line} 44 and a first and optionally further explosions in the reactor chamber 5, the following procedure is preferably followed. _{[00121] First, the filter device 2 is cleaned, whereby, with} the valve 32 preferably closed, the filter condensate _{collects in front of the valve 32. The transport device, specifically the rotary valve 7, the feed line} 44 and the reactor chamber 5, optionally with the expansion chamber 23, are then or have already been evacuated. Then, if not already done, the valve 33 is closed and the valve 32 is opened. Due to the negative pressure and optionally also with the aid of gravity, the filter condensate to be passivated is then conveyed into the transport device, here the rotary valve housing 27. 31257N1PCT – 31.10.2024 _{[00122] Then, valve 32 is closed again and valve 33 is opened} , and the filter condensate to be passivated _{is conveyed into the feed line 44 by the rotary valve 7. Then, preferably, valve 33 is also closed again} . _{[00123] With the aid of the pressure accumulator 45, a pressure surge is generated in the feed line 44} , preferably using compressed air, such as ambient air. _{[00124] The filter condensate in the feed line 44 is swirled , and, as described above, this alone preferably triggers a} pre-explosion. If necessary, this can also be assisted by an ignition device. _{[00125] As a result, the remaining filter condensate or particles are distributed} in the interconnected space comprising the feed line 44 and the reactor chamber 5, and optionally also the expansion chamber 23. _{[00126] A first and optionally further explosions are then carried out in the reactor chamber 5 and optionally the expansion chamber 23} in the manner described. _{[00127] The passivated filter condensate is then conveyed into the collection container 9} or partially into the collection container 50, if provided. The collection container can be removed, and the passivated filter material can then be disposed of. _{[00128] An exemplary size of the reactor alone (without the feed line)} is a volume of 12 dm ³ . A bulk material to be passivated can, for example, have a volume of 20 ml. 31257N1PCT – 31.10.2024 _{[00129] If the filter material to be passivated consists essentially or entirely of} titanium, the titanium is converted to TiO2 with the aid of oxygen. In the _{case of aluminum as a further or sole essential component, the aluminum is converted to Al2O3 with the aid of oxygen. The filter condensate to be passivated} can consist of other materials/metals besides titanium and/or aluminum, which are reacted accordingly with oxygen. These can be, for example, cobalt-chromium, copper, _{magnesium, nickel, tungsten, stainless steel, case-hardening steel, and tool steel in particular} . A combination of two or more of the mentioned materials, in particular the mentioned pure metals, can be present if the additive manufacturing is carried out with several of the mentioned materials or a corresponding alloy. _{[00130] A stoichiometric concentration of the metal relative to the air} mass, when the oxygen is supplied only by ambient air, can be calculated as follows: _{[00131] Cstöch,Mass is the amount of metal that can (still) be converted by the amount of air to} maintain the stoichiometric ratio. Here, ^ _air is the air density. The air density is known to be 1.292 kg/m ³ under standard conditions. _{[00132] The stoichiometrically required air volume, Cstöch,Vol, can be calculated in further} detail as follows: ^ _{^^ö^^,^^^ = ^^^^^^^ × ^^^^^^^ × 1000/(^^^^,^^ × ^^^ × 100 ^^^. −% /^^^),} 31257N1PCT – 31.10.2024 where M is the molar mass, n the number of moles, V _mol the molar volume and ^ _^^ the concentration of oxygen in the air. Furthermore, the molar volume is known to be _{22.4 dm3 at standard physical conditions of 0 °C and 1.01325 bar. The concentration of oxygen is known to be 21 vol.%.} From this the following table can be developed Molar mass M _{Number of moles Cstoch.Vol} Cstoch.Mass [g/mol] [gmetal/m ³ air] [gmetal/kg air] Titanium combustion T _{i 48 1 450 348 O2 32 1} Aluminum combustion A _{l 27 2 337.5 261 O2 32 1.5 [00133] With regard to the filter condensate, a correction must then be made with regard to the metal it contains} . The correction must be made using the parameters of bulk density, the proportion of the metal in question in the bulk mixture, and the bulk volume. 31257N1PCT – 31.10.2024 List of reference symbols _{1 Reactor device 29 Front side 2 Filter device 30 Disc 3 Filter condensate 31 Cell wheel chamber 4 Reactor housing 32 Valve 5 Reactor chamber 33 Valve} 6 _{Filter device connection 34 Valve 7 Portioning device 35 Valve} 8 Collection chamber connection _{36 Spring} element _{9 Collection chamber 37 Rotation axis 10 Shaft 38 Closure 11 Reaction chamber 39 Spring element} 12 Discharge chamber 40 Reactor _{base 13 Circumferential section 41 Ignition electrodes 14 Circumferential surface 42 Ignition electrodes 15 Receptacle area 43 Cyclone separator 16 Bushing} 44 Feed line 17 Longitudinal axis 45 Pressure _{accumulator 18 Rotation axis 46 Valve 19 Recess 47 Valve 20 Through hole 48 Container 21 Curvature 49 Exhaust air filter 22 Edge area 50} Collection chamber _{23 Extension chamber 51 Valve 24 Temperature sensor 52 Line 25 Pressure sensor 53 Line 26 Connection 27 Cell wheel housing L Length 28 Cell wheel d Diameter} 31257N1PCT – 31.10.2024

Claims

Claims _{1. Method for passivating a filter condensate (3) from a filter device (2) arranged in a} gas duct of a device for additive manufacturing by carrying out a chemical reaction between the filter condensate (3) and an oxidizing agent in a reactor _{device (1), wherein the reactor device (1) preferably has a feed line (44), a reactor chamber (5) with a filter device connection (6) for establishing a transportable connection between the reactor} device (1) and the filter device (2), and a collection chamber _{connection (8) for establishing a transportable connection between} the reactor device (1) and a collection chamber (9) for receiving passivated filter condensate (3), wherein the preferably provided feed line (44) and/or the reactor chamber (5) are designed to be pressure-resistant, the preferably provided feed line (44) and/or the reactor _{chamber (5) are separated from the environment to carry out the passivation} and ignition is carried out, wherein a first amount of filter condensate (3) and a second amount of oxidizing agent _{are introduced in portions into the preferably provided supply line (44)} and/or into the reactor chamber (5), characterized in that, to carry out the passivation, the first amount is further stoichiometrically adjusted to the second amount such that an explosive mixture is achieved and that the passivation is carried out by triggering an explosion. _{2. Method according to claim 1, characterized in that, if the supply line (44) is provided, the explosion is carried out as a pre-explosion in the supply line (44) and/or as a first and then optionally further} explosion in the reactor chamber (5). 31257N1PCT – 31.10.2024 _{3. Method according to one of the preceding claims, characterized in that the pre-explosion and/or the first and optionally further explosion is carried out by means of introducing the second and optionally} third etc. quantity. _{4. Method for passivating a filter condensate (3) from a filter device (2) arranged in a} gas duct of a device for additive manufacturing by carrying out a chemical reaction between the _{filter condensate (3) and an oxidizing agent in a reactor device (1), wherein the reactor device (1) has a reactor chamber (5) with} a filter device connection (6) for establishing a transportable connection between the reactor device (1) and the filter _{device (2), preferably by means of a feed line (44), and a collecting chamber connection (8) for establishing a transportable connection} between the reactor device (1) and a collecting chamber _{(9) for receiving passivated filter condensate (3), wherein} the reactor chamber (5) can be designed to be pressure-resistant, is separated from the environment to carry out the passivation, and an ignition is carried out for passivation, wherein further process gas conveyed in the gas duct, after leaving a production chamber, in addition to first, at the additive manufacturing chemically modified particles also comprises second, unmodified particles, characterized in that _{a separation device is arranged further upstream of the filter device (2)} for separating second, chemically unmodified particles. _{5. The method according to claim 4, characterized in that the separation device is designed as a cyclone or impact separator.} 31257N1PCT – 31.10.2024 _{6. Method according to one of the preceding claims, characterized in that after passivation, in particular after a first explosion, the reactor chamber (5) is evacuated under vacuum} . _{7. Method according to claim 6, characterized in that a medium led out of the reactor chamber (5) with the} vacuum evacuation is passed through a suspended matter filter to separate _{suspended matter contained in the medium. 8. Method according to claim 7, characterized in that the suspended matter separated at the} suspended matter filter _{is transported into the collection chamber (9, 50) by means of a flow reversal. 9. Method according to one of the preceding claims, characterized in} that the passivation is carried out several times by bringing about the explosion with respect to the same first quantity. _{10. The method according to one of the preceding claims, characterized in} that prior to triggering the pre-explosion and/or the first and optionally further explosion, the first _{quantity is swirled up in the feed line (44) and/or the reactor chamber (3)} . _{11. The method according to claim 10, characterized in that swirling up is carried out to prepare for} each explosion. 31257N1PCT – 31.10.2024 _{12. Method according to one of the preceding claims, characterized in that a third or further amount of oxidizing agent is introduced into the reactor chamber (3) in preparation for each explosion} . _{13. Method according to one of the preceding claims, characterized in} that a characteristic quantity _{is measured in the feed line (44)} and/or in the reactor chamber (3). _{14. Method according to claim 13, characterized in that the characteristic} quantity is the pressure and/or a temperature and/or an oxygen content. _{15. Method according to one of the preceding claims, characterized in that the passivation by inducing the explosion is repeated with regard to the same first amount as} long as an exceeding of a predetermined measured value is measured during the explosion. _{16. Method according to one of the preceding claims, characterized in that the first amount is 5 to 25 ml. 17. A method according to any one of the preceding claims, characterized in that the oxidizing agent is oxygen, which is optionally introduced as} part of the ambient air. _{18. A method according to any one of claims 10 to 17, characterized in} that the explosion is triggered at a predetermined time interval from the start of the turbulence. 31257N1PCT – 31.10.2024 _{19. Method according to one of the preceding claims, characterized in} that the explosion is triggered by an ignition spark. _{20. Method according to claim 19, characterized in that the ignition spark} is activated over a specific period of time. _{21. Method according to claim 20, characterized in that the period of time} is determined as a function of the recorded measured value. _{22. Method according to one of the preceding claims, characterized in} that the feed line (44) and/or the reactor chamber (3) is substantially cylindrical, with a length (L) and a _{diameter (d). 23. Method according to claim 22, characterized in that the reactor chamber (3) has a ratio of length (L) to diameter (d) of four or} less. _{24. Method according to one of claims 1 to 21, characterized in} that the reactor chamber (3) is substantially spherical. _{25. Reactor device (1) for passivating a filter condensate from a} filter device arranged in a gas duct of a device for additive manufacturing by carrying out a chemical reaction between the filter condensate (3) and an oxidizing agent, wherein the reactor _{device (1) has a reactor chamber (5) and preferably a feed line (44) leading to the} reactor chamber (5), further comprising a reactor chamber (5) with a filter device connection (6) for producing 31257N1PCT – 31.10.2024 a fluidic connection between the reactor device _{(1) and the filter device (2) and a collecting chamber} connection (8) for establishing a fluidic connection between the reactor device (1) and a collecting chamber (9) for receiving passivated filter condensate (3), characterized in that _{the preferably provided feed line (44) and/or the reactor} chamber (5) and preferably an ignition device in the feed line _{(44) and/or the reactor chamber (5) are designed to carry out a controlled explosion in the feed line (44) and/or the reactor chamber (5), wherein the feed line (44) and/or the reactor chamber (5) are designed to be correspondingly pressure-resistant. 26. Reactor device (1) according to claim 25, characterized in that} a first amount of filter condensate (3) and a second amount of oxidizing _{agent can be introduced in portions into the feed line (44) and/or into the reactor} chamber (5). _{27. Reactor device (1) according to one of claims 25 or 26, characterized in that a swirling of the first amount in the feed line (44) and/or in the reactor chamber (3) can be carried out. 28. Reactor device (1) according to one of claims 25 to 27, characterized in} that the ignition device relating to the reactor chamber (5) is arranged in a lower region, preferably a lower third, of the reactor chamber (5). _{29. Reactor device (1) according to one of claims 25 to 28, characterized in that a reactor bottom (40) is arranged between a first and a} 31257N1PCT – 31.10.2024 second operating position, wherein the reactor base (40) forms part of a reaction _{chamber (11) in the first operating position and part of a discharge chamber (12) in the second operating position,} and the subdivision can be removed during the displacement of the reactor base (40). 31257N1PCT – 31.10.2024