Method for passivating a filter condensate, and reactor device for passivating the filter condensate

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 Field of technology

[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 supply 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 supply line and / or the reactor chamber are designed to be pressure-resistant, the preferably provided supply line and / or the reactor chamber are separated from the environment to carry out the passivation, and an ignition is carried out,wherein a first amount of filter condensate and a second amount of oxidizing agent are introduced in portions into the preferably provided feed 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 space 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] The invention further relates to a reactor device for passivating a filter condensate from a filter device arranged in a gas duct of an additive manufacturing device 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 additive manufacturing facilities, especially in facilities 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, see WO 2021 / 104927 A1 (US 2022 / 0362691 A1). When additive manufacturing is carried out using laser welding, for example, laser welding fumes are generated that must be filtered.

[0005] The gas can in particular be a protective gas, an inert gas such as argon or nitrogen.

[0006] During additive manufacturing, unused particles, particularly (metal) particles, hereinafter also referred to as raw powder, and any reaction products or spalling products or ejections from the melt pool are carried out of the process chamber by the process gas. The spalling products and / or ejections from the melt pool are hereinafter also referred to collectively as splashes (splash, splatter). The splashes and any smoke generated, particularly laser welding fumes 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 fumes. 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 risk of fire and explosion. 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 system 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] With the known methods and devices for passivating filter condensate, a process control is required that avoids explosive development as much as possible. Flooding with oil or water or the addition of neutralizing agents has already been proposed, even when filter condensate has already been transferred from the passivation device to the collection 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] Based on a prior art, such as that known from the aforementioned DE 102020000501 A1, the object of the invention is to provide a method for passivating a 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 problem is initially and essentially solved by the fact that, in order to carry out the passivation, the first quantity is further adjusted stoichiometrically 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] 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 the ratio of oxygen to flammable or explosive components. Preferably, the adjustment is such that the mixture is clearly within the range required for the explosion. The aim is to achieve the most complete combustion or oxidation possible (even in the first explosion). On the other hand, increased pressure due to an excessively high oxygen content should be avoided. Passivation is carried out accordingly by triggering the explosion. According to the process described here, the path of triggering an explosion for passivation is thus deliberately, specifically, and systematically taken.The inherent explosive nature of the filter condensate is specifically utilized for passivation. Unlike conventional measures, the reactivity of the condensate is not masked by the addition of materials or sufficiently demixed by additives. Instead, the reactivity of the condensate or the individual particles contained therein is specifically reduced to a level that is no longer relevant.

[0013] Stoichiometric adjustment does not necessarily mean, although preferably, that the exact stoichiometric ratio required to trigger the explosion is achieved. It can also be 31257N1PCT – 31.10.2024 limits, a sub-stoichiometric and especially a super-stoichiometric ratio can be set. For example, in additive manufacturing with titanium powder, with a quantity of 0.2 g (corresponding to 1 cm³) of titanium filter condensate obtained, an air requirement of 2,22 dm³.

[0014] The process described here has the advantage that, with the exception of the second amount, no additives need to be introduced. Since, as explained further below, the second amount can preferably be air, in particular ambient air, this provides a simple and cost-effective method for carrying out the passivation. Based on a stoichiometrically required amount of oxygen, a required amount of air can be determined even if the oxygen is provided by air, such as ambient air.

[0015] In particular, a comparatively low energy input is required to achieve passivation. Since one or possibly several explosions also very effectively convert flammable or explosive components in the filter condensate into a neutral state, final passivation in the reactor chamber can also be achieved. No further special precautions need to be taken in the collection vessel.

[0016] With regard to a further method, in which it is not necessarily necessary to carry out a controlled explosion, but this is preferably provided, it is intended that a separation device is arranged further upstream of the filter device for the separation of second, chemically unaltered particles. 31257N1PCT – 31.10.2024

[0017] This allows for a more predictable passivation process. The filter condensate to be passivated has a more homogeneous composition. Particularly when proceeding with a method described further here, the second quantity required to carry out a controlled explosion can 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 so that the supply line and / or the reactor chamber are explosion-proof. This applies in particular to the multiple explosions for which the reactor facility is designed. This may also apply 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 the 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, precedes a further explosion in the reactor chamber, also referred to here as the first explosion, which initially and essentially occurs in the feed line. As a rule, the pre-explosion does not achieve complete passivation of the filter condensate with regard to the quantity of filter condensate introduced into the feed line. However, a substantial conversion of a relevant portion of this quantity is achieved through the pre-explosion in the sense of passivation. If the feed line and the reactor chamber are not separated from each other, as is preferred, the pre-explosion also drives the filter condensate further into the reactor chamber.The pre-explosion can also trigger another explosion in the reactor chamber. This additional explosion is also referred to below as the first explosion. The pre-explosion is essentially an initial explosion in the feed line. Since the required stoichiometric ratio is usually not achieved in the feed line, complete conversion cannot usually be achieved by the pre-explosion.

[0022] The pre-explosion preferably only occurs or is triggered when new filter condensate, i.e., a new initial amount 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, particularly 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, if necessary, second, third, etc. explosion in the reactor chamber, favorable passivation can be achieved.

[0025] During the pre-explosion, it is further preferred, as already stated, that the feed line is not separated from the reactor chamber. Although 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 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, is closed, as is a shut-off valve downstream of the reactor chamber, the thus interconnected space consisting of 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 upstream of the transport device, in particular the rotary valve, in the direction of flow, allowing the filter condensate to enter the transport device, preferably the rotary valve. A shut-off valve downstream of the transport device but upstream of the supply line is preferably also closed beforehand.

[0028] With the aid of the transport device, the filter condensate is portioned in anticipation of a subsequent explosion in such a way that, taking into account the volume of the supply line and / or the reactor chamber, the required ratio to the oxygen then supplied, particularly as a proportion of air, is achieved. This is based on the required stoichiometric ratio. Alternatively, the supplied oxygen (air) can also be determined based on the amount of filter condensate introduced.

[0029] In a further step, the shutoff valve upstream of the transport device is closed, and the shutoff 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. This can be driven by gravity as well as, in the sense of and / or, a pressure difference between the transport device and the previously evacuated feed line, together with the reactor chamber.

[0030] With regard to the pre-explosion, the filter condensate introduced into the supply line is preferably subjected to a pressure surge, preferably based on ambient air. However, a pressure surge can also be applied with pure oxygen alone 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 swirl. This can further lead, particularly due to the swirling, to friction between the individual particles of the filter condensate, or to friction between the particles on the wall of the supply line or with the supplied medium, thereby resulting in the ignition of the filter condensate. In any case, the pre-explosion already achieves significant passivation. The pre-explosion and an initial explosion, possibly caused by it, can already achieve very extensive passivation—depending on the composition and / or quantity of the filter condensate, possibly even sufficient passivation.In particular, it is preferred that the energy required for such an explosion, in particular a pre-explosion, with regard to ignition is generated only by the frictional power resulting from the turbulence.

[0032] The ignition and triggering of a pre-explosion in the feed 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 separated, 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 feed 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 subjected, as well as by the geometry of the inlet opening and / or the geometry of the feed line.

[0033] Preferably, the medium contained in the supply line is further injected by the pressure surge or otherwise, in particular ambient air 31257N1PCT – 31.10.2024 Filter condensate, if necessary after the pre-explosion, is conveyed from the feed line into the reactor chamber.

[0034] The amount of compressed air supplied for the preferred pressure surge, preferably supplied from a pressure accumulator, can have a volume of, for example, 10 to 15, preferably approximately 12 to 14, more preferably 13 liters. The pressure level in the pressure accumulator can be significantly higher than 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 amount of supplied medium (air) is selected such that after supply of the medium in the specified amount, a pressure of approximately 950 millibars, but also up to approximately 1300 mbar, is established in the supply line and the reactor chamber.

[0036] It can also be calculated in further detail, if corresponding data is recorded by sensors, via a control device and ultimately determined 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 established.

[0037] Although the injection of compressed air into the supply line in the manner described generally results in self-ignition of the filter condensate, a further development also provides that, in addition to or as an alternative to the injection, an ignition spark in the supply line or in the reactor chamber is used to trigger, in particular, 31257N1PCT – 31.10.2024 the pre-explosion or the first explosion. Multiple ignition sparks can also be generated, particularly in both the feed line and the reactor chamber.

[0038] After ignition and the resulting pre-explosion and / or first and possibly 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. Afterward, the supply line, including the reactor chamber, is preferably (re)evacuated using a vacuum pump. This waiting period is based on empirical values observed regarding the time required until suspended parts have essentially settled again. Depending on the material being processed in additive manufacturing, different periods may occur.

[0039] The evacuated medium is preferably passed through a separate extraction filter. In the extraction filter, particles—in this case, passivated particles—are continuously and usually present in the supply line and / or reactor chamber after the explosion. The particles thus separated may also contain particles extracted during the evacuation that had previously settled on the walls or floor. The purified medium can, for example, be discharged into the environment of the system. 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 system of the additive manufacturing system itself.

[0041] The extraction filter itself is also preferably cleaned, for example, depending on a predetermined pressure drop occurring across the filter. This can be achieved, in particular, by a gas pressure pulse, more preferably a protective gas pressure pulse. In this case, the filtrate, which is essentially blown off by the extraction filter, is conveyed into the feed line from the reactor chamber to the collection vessel and thus ultimately into the collection vessel.

[0042] In a first embodiment of the process, an explosion, in the sense of a first explosion, is triggered immediately in the reactor chamber. In this case, no (pre-)explosion has been triggered beforehand. With this type of process, the feed line can be comparatively short, or even nonexistent. 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 may 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 causing the first explosion with respect to the same first quantity. This first explosion, which is then followed by the corresponding second and optionally third, etc. explosion, is carried out in the reactor chamber. It may occasionally occur that the first controlled explosion carried out initially has not yet led to complete or sufficient passivation of the first quantity. In this case, the same first quantity can be detonated again, whereby 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 additional amount of oxidizing agent can preferably be introduced directly into the reactor chamber, preferably also via a corresponding line leading into the reactor chamber.

[0045] Preferably, the reactor chamber is also equipped 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 execution 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 execution 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, a count of the explosions can also be carried out simultaneously. In addition, however, the 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, in the reactor chamber, as long as the same first quantity is exceeded, as long as a predetermined temperature and / or pressure and / or oxygen content falls below a predetermined value 31257N1PCT – 31.10.2024 is measured during the explosion. As long as a significant portion of non-passivated filter condensate is still present in the first quantity, the temperature and / or pressure exceeds a predetermined value during an explosion, causing the oxygen content to fall. With regard to the oxygen content, it may be advisable to monitor for the oxygen content falling below a predetermined value. If this oxygen content is not exceeded, this alone or in combination with one of the other values can also 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 absence of a drop in oxygen content indicates that sufficient passivation was already achieved during the previous explosion. If 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 this can be used as a trigger to consider passivation complete and to transfer the passivated filter condensate from the reactor chamber to the collection chamber.

[0047] The specified temperature and / or pressure, and possibly also the oxygen content under consideration, may vary depending on the specific additive manufacturing process in which the reactor device is integrated. They can be determined empirically.

[0048] The filter condensate in a conventional additive manufacturing system may contain unused additive manufacturing material, known as raw powder, which may also be recyclable. Es31257N1PCT – 31.10.2024 Within the scope of the disclosure given here, it is preferred to separate raw powder, 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 also in the interest of better predictability or determinability of the required stoichiometric ratio between filter condensate and oxygen. Several possibilities exist for this. A simple possibility is to first pass a quantity of gas discharged from 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 effectively separated in the separator.The separation process can particularly benefit from 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 nanoscale. 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 maintained at a predictable level, so that stoichiometric adjustment can also be carried out more reliably.

[0049] The amount of filter condensate passivated in the described manner can vary. For an initial design, a quantity between 5 and 25 ml is preferred. However, by selecting the appropriate size of the reactor chamber, possibly 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 even 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 itself, the triggering of the explosion is initiated. The stirring is preferably also carried out, as already explained, by the introduction, preferably by injection, of the second quantity of the oxidizing agent, i.e. preferably by the introduction of air. The stirring is carried out in such a way that an explosive dust cloud is created in the supply line and / or the reactor chamber. If the explosion is not carried out immediately with the stirring, but rather with a certain time interval after the initiated stirring, 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, particularly an air jet. With regard to the first and possibly second and further explosions (in the reactor chamber), one embodiment provides for the explosion to be triggered by an ignition device, such as an ignition device generating an ignition spark. The ignition spark can be generated, for example, by a spark plug or a device corresponding to a spark plug. The ignition device can also be designed, optionally only, to form a flame.According to a further version, as an alternative to ignition via an ignition device, it is provided that even in the case of an explosion only the first and possibly further explosion in the reactor chamber is triggered, 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] Additionally or alternatively, it is also preferred that the ignition spark or several ignition sparks are activated consecutively over a longer period of time. This also has a positive effect on the exploitation of the first and possibly second and subsequent explosions in particular. If necessary, several ignitions (explosions) can be achieved consecutively without having to run through a completely new cycle, i.e., in particular, without having to resuspend and / or inject a second quantity. 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] Despite the fact that the explosion is triggered by the ignition device, preferably with respect to the first explosion in the reactor chamber, the pre-explosion can also be triggered by an ignition device. 31257N1PCT – 31.10.2024

[0055] The period can be varied and determined depending on the pressure, temperature, and / or oxygen content measured during a previous explosion. If the pressure during a previous explosion is comparatively low, it is preferable to trigger the ignition spark(s) over a longer period.

[0056] The feed line and / or the reactor chamber can be substantially cylindrical, having a corresponding cylindrical length and 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 be produced during the resuspension process.

[0057] Preferably, the reactor chamber is designed to be relatively compact. A possible reactor chamber design is therefore 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 done with regard to 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 a spherical configuration.

[0059] With regard to the value ranges specified above and below, such as a volume range of 10 to 15 l, all intermediate values are also included, particularly in tenths, i.e. 10.1 l to 15 l, 10 l to 14.9 l, 10.2 l to 15 l, etc. The same applies, for example, to a value range such as that specified in 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 illustrates exemplary embodiments. 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 plane II in Fig. 1; Fig. 3 shows a longitudinal section along line III in Fig. 2; Fig. 4 shows a longitudinal section along plane IV of the reactor device shown in Fig. 1; 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 a section along the line IX in Fig. 8; Fig. 10 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 of a manufacturing facility for additive manufacturing with a filter device 2, a portioning device 7, and a reactor device 1. The filter device is, for example, connected downstream of a metal printing device (not shown) 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 – 31.10.2024

[0062] The system shown can also be used for other industrial facilities that produce reactive filter condensate, rather than in conjunction with metal pressure equipment. The exemplary structure shown below, particularly of the reactor device 1 and 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 then 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 of contaminants, which subsequently form, among other things, the filter condensate 3.

[0064] The filter condensate may, under certain circumstances and to a considerable extent, still contain raw powder that is to be used for additive manufacturing, and, for example, spatter, at least in previously known process configurations, which are also generally usable in the present case. In this context, it is advantageous, according to the system described here, 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 flow.

[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 – October 31, 2024 The separation device is configured such that material not consumed 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 unconsumed (unreacted) starting material and the spent filter condensate ultimately fed to the collection chamber can be exploited. 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 the claims of the present invention.

[0067] In order to clean the filter of the filter device 2 and to remove the filter condensate 3 that has settled 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 process gas flow and cleaned, for example, using 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 a defined pressure drop has been reached across a filter wall, as an indicator of the required cleaning, 31257N1PCT – 31.10.For example, a flushing medium can be directed onto the filter wall in order to flow through the filter wall in a 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 incorporated in its entirety into the disclosure of the present invention, also for the purpose of incorporating features disclosed therein into the 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 shut-off valve 32.Subsequently, the portioning device 7 is activated, so that the filter condensate 3 is transported into the reactor device 1 according to a first possible process sequence. Within the reactor device 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, valve 33 is closed and ambient air is preferably introduced into reactor device 1 as an oxidizing agent.

[0069] After the passivation process is complete, another valve 34 located downstream of the reactor device 1 is opened to convey the passivated filter condensate 3 from the reactor device 1 into a collection chamber 9. A further valve 35 is located downstream of the valve 34 between the reactor device 1 and the collection chamber 9. 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 already provides sufficient 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, 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 in relation to a Ro- 31257N1PCT – 31.10.2024. The frictional connection 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, acting in the axial direction of the rotational axis 37 of the cellular wheel 28, ensures that filter condensate 3 cannot escape from the cellular wheel chambers 31 of the cellular wheel lock into the environment. Furthermore, the position of the disc 30 is shifted or adjusted if material wear occurs due to friction between the cellular wheel 28 and the disc 30. The spring element 36 thus automatically adjusts the position of the disc 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 disc 30 on the other hand.

[0071] Although not shown here, a sluice consisting of two valves and a space arranged between them can also be used as the portioning device 7 instead of the illustrated rotary valve. The space between the valves determines the amount of filter condensate 3 portioned 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 a fluidization capability is provided, a nozzle can be provided for introducing a fluidizing gas, in particular air, into the reactor chamber.

[0073] Alternatively, the filter condensate can be introduced into the reactor chamber by injection, for example, using an inert gas or air as mentioned above. This can simultaneously stir up the fluid and, in the case of air, also introduce oxygen.

[0074] As can be seen particularly from Figure 3, in the case of the rotary valve, the rotary wheel 28 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, the upper one 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 cellular wheel chambers 31 is filled, is slightly inclined so that a chamber floor of the cellular wheel chamber 31 is not oriented horizontally. This can contribute to the complete emptying of the cellular wheel chamber 31 upon rotation of the cellular wheel 28 by 180 degrees, preventing any portions of the filter condensate 3 from remaining in the portioning device 7. Furthermore, if partial quantities of filter condensate 3 are located in a clearance between the cellular wheel 28 and the cellular wheel housing 27, these can be released by over-rotating it 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 shut off first. Then, only the reactor device 1 could be evacuated, without simultaneously evacuating the portioning device 7.When the rotary valve is actuated, the filter condensate 3 would then fall onto the closed valve 33 and, after the valve 33 is opened, would 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 storage locations 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 storage locations, 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 similarly has a collection chamber connection 8, 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 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 making the reactor chamber 5 explosion-proof, the wall or the housing is designed such that it can withstand elevated 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 extends through the reactor chamber 5 and, relative to the rotational position of the shaft 10 shown in Figures 4 and 5, contacts a portion 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 chamber 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 floor 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 outer diameters along its longitudinal extent, i.e., parallel to its rotational axis 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 rotation axis 18 of the shaft 10.

[0084] The peripheral portion 13 of the shaft 10 projecting into the reaction chamber 11 has a receiving area 15 for filter condensate 3 filled into the reactor device 1. The receiving area 15 is, for example, a concave material recess.

[0085] As can be seen in particular from Figures 5 to 7, a total of four such receptacles 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 rotating the shaft 10 by 90 degrees around the rotation axis 18, a different receiving area 15 of a different circumferential partial area 13 of the shaft 10 can 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. Alternatively or additionally, a gas sensor for measuring an O2 content can also be provided. Using one, several, or all of these measured values—as will be explained below—the one or more explosion processes of the passivation process of filter condensate 3 within the reactor device 1 can be monitored.

[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 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 flows via the feed line 44 into the reaction chamber 11, which is spatially separated from the discharge chamber 12 or at least an adjoining line section by the form-fitting and force-fitting engagement of the bushing 16 with the circumferential portion 13 of the shaft 10. This 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 and essentially hits the receiving area 15 of the shaft 10 directly 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 is propelled upwards, i.e.optionally transported toward 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 the pressure sensor 25), the supply of oxidant 31257N1PCT – 31.10.2024 through the connections 26 is stopped. 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 pressure are preferably also measured continuously during the explosion. If the temperature and / or 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, i.e., still has residual chemical reactivity that poses a fire hazard.Therefore, the explosion passivation cycle is performed a second time by again bringing the same portion of filter condensate 3 located in the reaction chamber 11 into contact with the oxidizing agent. 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 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 filter condensate 3, it is possible to determine in advance the required amount of oxidizing agent 31257N1PCT – 31.10.2024 for complete passivation of the first amount, filter condensate 3, and then to calculate a number of passivation cycles, i.e., required explosions, necessary to passivate the total amount 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 passivation is started earlier and / or completed more quickly. The heating of the oxidizing agent can be carried out, for example, with the aid of heating elements that heat a wall of a reaction chamber feed line. It is also preferably possible, for example, to design a wall of a reaction chamber feed line as a heat exchanger, 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 room 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 designated 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, the intermediate position shown in Figure 6 is initially reached (among others), in which the reaction chamber 11 has a flow connection to the discharge chamber 12 of the reactor chamber 5. The filter condensate 3 collected in the receiving area 15 of the shaft 10 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 in this way within the reactor chamber 5.

[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 portion 13 of the shaft 10 and the reactor housing 4, a bushing 16 is again 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, in Figure 8—continues in the direction of the longitudinal extension of the rotational axis 18 of the shaft 10. As a result, the curved circumferential portion 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. Thus, an overall annular receiving area 15 is formed. 31257N1PCT – 31.10.2024 the curvature 21 of the shaft 10, which serves to receive the filter condensate 3.

[0097] In combination with the curvature 21, the shaft 10 has a through-bore 20 which runs, for example, orthogonal to the axis of rotation 18 of the shaft 10, i.e., in the direction of rotation of the shaft 10, through the shaft 10. The through-bore 20 is spatially separated from the curvature 21 or from two opposing curvatures 21 with respect to the circumferential surface 14 of the shaft 10. In particular, the design is such, as can be seen, for example, from Figure 8, 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 opposing 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 region of the through-bore 20 slides 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 spirally within the reaction chamber 11 and the connected extension chamber 23.

[0100] 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 also be seen from the figures of the drawing, the expansion chamber 23, or the reactor chamber as a whole, has a considerable height or length L. The expansion chamber 23 or the reactor chamber is preferably arranged vertically in its longitudinal extent, which is a multiple of a given width or diameter d (relative to the interior space). A ratio of length to width or diameter d of 4 or less is further preferred. Fluidized 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 – October 31, 2024.

[0101] As can be seen particularly 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 explosions, etc., is preferably initiated deliberately, or the start of passivation is assisted 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 near the actual reactor chamber.

[0102] 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.

[0103] Alternatively, a conventional spark plug or a piezo spark generator can be used.

[0104] 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, the proportion of the second quantity, in particular air, to be added can be determined mathematically.

[0105] Passivation by explosion is preferably carried out several times in succession. In preparation for each explosion, the fluidization is also carried out. 31257N1PCT – 31.10.2024

[0106] In preparation for each explosion, a further, additional, third or further amount of oxidizer as specified above may be introduced into the reactor chamber 5.

[0107] The temperature in the reactor chamber 5 is measured by the temperature sensor 24, preferably continuously or at least at specific intervals. The measurement is carried out in such a way that the temperature reached during an explosion can be determined.

[0108] 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.

[0109] The first explosion is repeated in the reactor chamber 5 with respect to the first quantity introduced, without part of the quantity being transferred into the collection chamber 9 or a further quantity 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.

[0110] 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.

[0111] The explosion is preferably triggered at a predetermined time interval from the beginning of the resuspension. A complete resuspension should have developed before the explosion is triggered. However, the filter condensate 3 should be condensed when the explosion is triggered. 31257N1PCT – 31.10.2024 still be in the stirred-up state. It should ideally not have settled back to the ground, or not to a significant extent.

[0112] The explosion is preferably triggered by the previously described ignition electrodes 41, 42 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 can be determined, in particular, as a function of the pressure measured during an explosion.

[0113] Referring 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 supply line 44.

[0114] 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 arise as already described above with reference to Figure 1. Reference is made to this.

[0115] This also applies in the same way to the transport device, here the portioning device 7, and the upstream and downstream valves.

[0116] It can be seen that in this embodiment the supply line 44 is significantly longer than in the system according to Figure 1.

[0117] Associated with the supply line 44, 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

[0118] It is also important that an exhaust air filter 49 is provided connected to the reactor chamber 5, which can be pressurized with a separate vacuum device not shown in detail here, in particular a separate vacuum pump.

[0119] Associated with the exhaust air filter 49, a further, separate collection chamber 50 can also be provided, which can also be shut off via a valve 51. A line 52 leads to or from the exhaust air filter 49 to the collection chamber 50. As an alternative to the collection chamber 50, filtrate falling off from the exhaust air filter 49 in countercurrent operation, as also described above, could 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.

[0120] When carrying out the process with a pre-explosion in the feed line 44 and a first and possibly further explosions in the reactor chamber 5, the following procedure is preferably used.

[0121] First, the filter device 2 is cleaned, whereby, with valve 32 preferably closed, the filter condensate accumulates 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 evacuated 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, if necessary, 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

[0122] 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 via the rotary valve 7. Then, preferably, valve 33 is also closed again.

[0123] With the help of the pressure accumulator 45, a pressure surge is generated in the supply line 44, preferably by means of compressed air, such as ambient air.

[0124] The filter condensate in the supply line 44 is swirled, and, as described above, this preferably triggers a pre-explosion alone. If necessary, this can also be assisted by an ignition device.

[0125] As a result, the remaining filter condensate or particles are distributed in the interconnected space consisting of the feed line 44 and the reactor chamber 5, and possibly also the extension chamber 23.

[0126] In the reactor chamber 5 and, if applicable, the expansion chamber 23, a first and, if applicable, further explosions are then carried out in the manner described.

[0127] The passivated filter condensate is then conveyed into the collection tank 9 or, where provided, partially into the collection tank 50. The collection tank can be removed, and the passivated filter material can then be disposed of.

[0128] An example 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

[0129] If the filter material to be passivated consists essentially or entirely of titanium, the titanium is converted to TiO2 with the aid of oxygen. If aluminum is a further or sole essential component, the aluminum is converted to Al2O3 with the aid of oxygen. In addition to titanium and / or aluminum, the filter condensate to be passivated can also consist of other materials / metals that are reacted with oxygen. These can include, for example, cobalt-chromium, copper, magnesium, nickel, tungsten, stainless steel, case-hardened steel, and tool steel in particular. A combination of two or more of the aforementioned materials, in particular the aforementioned pure metals, can be present if additive manufacturing is carried out with several of the aforementioned materials or a corresponding alloy.

[0130] A stoichiometric concentration of the metal relative to the air mass, when oxygen is supplied only by ambient air, can be calculated as follows

[0131] Cstöch,Mass is the amount of metal that can (still) be converted by the amount of air to maintain the stoichiometric ratio. Here, ^ Luft the air density. The air density under normal conditions is known to be 1.292 kg / m 3 .

[0132] 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 is 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 Molanzahl Cstöch.Vol Cstöch.Mass [g / mol] [gMetal / m 3 Air] [gMetal / kgAir] Titanium combustion T i 48 1 450 348 O2 32 1 Aluminum combustion A l 27 2 337,5 261 O2 32 1,5

[0133] 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 material 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. A method for passivating a filter condensate (3) from a filter device (2) arranged in a gas duct of an additive manufacturing device 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 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 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 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 environment to carry out the passivation, and an 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). The method according to claim 1, 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 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. amount.

4. Method for passivating a filter condensate (3) from a filter device (2) arranged in a gas duct of an apparatus 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 supply line (44).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 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, contains not only first particles chemically modified during additive manufacturing but also second, unmodified particles, characterized in that a separation device is arranged further upstream of the filter device (2) for separating second, unmodified particles.

5. 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 inducing the explosion with respect to the same first quantity.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. 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 respect to the same first amount as long as an exceedance 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.Method according to one of the preceding claims, characterized in that the oxidizing agent is oxygen, which is optionally introduced as part of the ambient air.

18. Method according to 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 certain 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) urchmesser (d).

23. The 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. The method according to one of claims 1 to 21, characterized in that the reactor chamber (3) is substantially spherical.

25. A 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 up of the first quantity in the feed line (44) and / or in the reactor chamber (3) is possible.

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 base (40) is arranged between a first and a31257N1PCT - 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

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