WO2022029079A1

WO2022029079A1 - Gas purification device and method for purifying a gas

Info

Publication number: WO2022029079A1
Application number: PCT/EP2021/071570
Authority: WO
Inventors: Manfred Krukenberg; Dirk Wandke; Ronny Lettke; Jan-Hendrik Hellmold
Original assignee: Cinogy Gmbh
Priority date: 2020-08-04
Filing date: 2021-08-02
Publication date: 2022-02-10
Also published as: DE102020120582A1

Abstract

The invention relates to a gas purification device (2) for purifying a gas, comprising at least one catalytic converter assembly (12), wherein the gas purification device has a) a plasma generating device (4) for generating a plasma, said plasma generating device (4) having at least two electrodes (6), between which at least one gap (8) is formed where the plasma is generated, and b) the plasma generating device (4) and the at least one catalytic converter assembly (12) are arranged and designed such that gas to be purified flows through the gap (8) and the at least one catalytic converter assembly (12) during the operation of the gas purification device (2), and the at least one catalytic converter device is arranged upstream and/or downstream of the plasma generating device (4) in the flow direction (S) of the gas to be purified and/or is formed as part of the plasma generating device (4).

Description

Gas cleaning device and method for cleaning a gas

The invention relates to a gas purification device which has at least one catalyst arrangement. According to a further aspect, the invention relates to a method for cleaning a gas.

Gases are used or generated in a wide variety of technical applications. Depending on the determination of the gas in question, it may be useful or even necessary to clean the gas.

Purification of the gas is understood in particular to mean that certain undesirable molecules, but also biological contaminants such as bacteria, viruses, allergens or the like, are removed from the gas or at least their quantity is reduced.

Undesirable molecules can be toxic or harmful substances, such as formaldehyde, but also odorous substances or other harmless but disruptive substances.

An application to which this invention also relates in particular is the purification of air, for example room air. There is a need to clean the room air both in normal households and in particular in sensitive areas such as hospitals, medical practices, laboratories, clean rooms or the like. Further possible uses are, for example, public buildings, restaurants or the like.

In hospitals, for example in operating theaters or in isolation units for certain patients, the air in the room must be free of pathogenic germs such as viruses, bacteria, or fungi and their spores are cleaned to prevent infection of the patient or his environment.

One way of cleaning is by using filters, such as the so-called suspended matter or HEPA filters. These are able to filter out pathogens, but partly form a basis for filtered out bacteria, which can then colonize the filter membranes and possibly secrete substances that are hazardous to health. However, they are not able to filter gaseous molecules, in particular volatile organic compounds (VOC), from the air.

In addition, catalysts are used for gas cleaning, for example in exhaust gas cleaning systems. It is also known, for example, to use the photocatalytic activity of titanium dioxide to purify air. A disadvantage of this technology is the energy consumption for the commonly used UV radiation source and the fact that particulate contaminants can hardly be removed. In certain special applications, plasma is also used for air purification. However, the high temperatures associated with conventional plasma generation limit its applicability.

The object of the present invention is to provide more efficient cleaning of a gas, in particular air.

The invention solves the problem set by a gas cleaning device of the type mentioned at the outset, which is characterized in that it a) has a plasma generating device for generating a plasma, the plasma generating device having at least two electrodes, between which at least one gap is formed, in which the plasma generation takes place, and b) the plasma generation device and the at least one catalyst arrangement are arranged and set up in such a way that the gas to be cleaned flows through the gap and the at least one catalyst arrangement during operation of the gas cleaning device and the at least one catalyst device flows upstream and in the flow direction of the gas to be cleaned /or is arranged behind the plasma generating device and/or is designed as part of the plasma generating device. The applicant has found that a combination of plasma cleaning with catalytic cleaning of the gas to be cleaned enables surprisingly good and significantly better cleaning properties than catalyst or plasma treatment alone. Purification therefore takes place according to the invention in at least two stages. Before, after and/or during the plasma treatment of the gas to be cleaned, the gas is additionally cleaned by means of the catalyst arrangement. In the flow direction of the gas, for example, two cleaning stages with different effects are therefore connected in series.

By connecting several cleaning stages in series, the amount of impurities in the gas to be cleaned is reduced from one stage to the one behind it in the direction of flow, so that in particular the cleaning capacity is not exceeded and more efficient cleaning is possible.

In addition, there are organic substances that cannot be completely destroyed by either plasmatic or catalytic degradation alone, in particular mineralize them, i.e. convert them to carbon dioxide and water. For example, the catalytic purification of such substances produces a degradation product which is also undesirable and is only then destroyed by the plasma, or vice versa. In addition, some degradation products that are produced during a first catalytic cleaning step before the plasma treatment are then in turn not completely degraded in the plasma treatment. The resulting degradation products of the degradation products are then further or even completely degraded in a downstream second catalytic purification. The combination of the two different cleaning processes can also synergistically reduce or even completely destroy in particular those degradation products in the cleaned gas that could not be destroyed by the individual stages alone.

Both technologies also have different effective spectra. For example, plasma technology is more effective against particulate contaminants, whereas catalyst technology is sometimes more effective against gaseous contaminants. In this respect, the combination of the two technologies also leads to a broadening of the effective spectrum of the gas purification device. There the different technologies have different principles of action, but they complement each other even with contaminants of the same type, so that their removal from the gas is improved.

In addition, due to the combination, fewer cleaning stages can be used in order to achieve a good cleaning result, so that the design can also be chosen to be more compact and smaller.

The gas cleaning device is designed, for example, as an insert or module for a ventilation system, for example a building ventilation system. It can be used both for new buildings and as a retrofit part. According to a further aspect, the gas cleaning device can also be designed as a free-standing or suspended system for cleaning a gas, in particular room air. The gas cleaning device is preferably designed as a tabletop device which can be placed on a table in restaurants or offices, for example, in order to clean the room air and in particular to reduce or even completely prevent the transmission of pathogens from one person to another.

It is possible within the scope of the invention for a plurality of catalytic converter arrangements and/or a plurality of plasma generating devices to be present in a gas purification device.

The catalytic converter arrangement has at least one catalytic converter which is present in particular in powder form. The at least one catalyst is preferably arranged on a support, for example coated on it. The carrier is preferably designed so that the gas can flow through it, for example as a grating or expanded metal. The carrier preferably has a honeycomb structure. The carrier is particularly preferably a metal sheet folded or bent to form a honeycomb structure, for example made of aluminum or another material that is as little reactive as possible. The honeycombs preferably have a flow-through length of at least 0.5 cm, in particular at least 1 cm, particularly preferably at least 2 cm. The length that can be flowed through is preferably at most 20 cm, in particular at most 10 cm. The gas cleaning device preferably has a housing through which the gas to be cleaned flows. For this purpose, the housing has at least one inlet opening through which the gas flows into the gas purification device. It is preferred, but not necessary, for the gas purification device to have a suction device, for example a fan or a ventilator, which sucks gas into the housing through the at least one inlet opening. By means of such a suction device, in particular a stagnant gas, for example room air, can be introduced into the gas cleaning device in any appreciable quantities. At the same time, a flow rate of the gas through the gas cleaning device can be regulated by means of the suction device and can preferably be set by means of an electronic control device assigned to the gas cleaning device. In this way, a flow rate of the gas to be cleaned that is useful or optimal for the function can be set.

The plasma generating device is arranged in the flow path of the gas. The gas flows through the at least one gap formed between the electrodes. The gas in the gap is partially ionized by the plasma discharge and thus converted into the plasma state.

The plasma generating device can also have a housing in which the electrodes are arranged. The gas flows into the housing through an opening and is swirled there, preferably by means of a grid arranged inside the housing and in front of the electrodes in the direction of flow. According to one embodiment, one electrode completely surrounds the other electrode, forming a circumferential gap, for example with an annular cross section.

According to a preferred embodiment, the plasma generating device is designed to generate a dielectrically impeded plasma discharge and at least one of the electrodes has a dielectric at least on its surface facing the gap. In such an embodiment, a housing surrounding the electrodes can preferably be dispensed with. This applies in particular when both electrodes are completely embedded in a dielectric. The dielectric is used to implement a dielectric barrier plasma discharge, which is also referred to as DBD (Dielectric Barrier Discharge). The dielectrically impeded plasma discharge is particularly advantageous because a cold plasma is generated in the process and the thermal load on the environment and the associated necessary insulation and design of the components for a hot plasma can therefore be dispensed with. In addition, the dielectric ensures in particular that the electrode does not pose any direct danger to the user due to the high voltage used.

If, which corresponds to one embodiment of the invention, one of the electrodes is in the form of a ground electrode, ie in particular grounded or at least has a lower electrical potential than the other electrode, preferably only the other electrode has a dielectric. This other electrode, to which an alternating voltage is applied during operation and which is also referred to as a high-voltage electrode, is preferably completely embedded in the dielectric. The ground electrode does not necessarily need a dielectric, since it does not have any dangerous potential even during operation. It is of course still possible that the ground electrode is also embedded in a dielectric. This makes sense, for example, in order to only have to keep one type of electrode available.

The fact that an electrode is completely embedded in a dielectric does not, of course, preclude necessary openings through the dielectric, for example for electrical contacting. The dielectric is preferably perforated exclusively for the purpose of bringing in an electrical line or because of a connection for such a line, for example a connection socket or the like.

According to one embodiment, at least one catalyst arrangement is located upstream and/or downstream of the plasma generating device in the direction of flow. According to a preferred embodiment, exactly one catalyst arrangement is located upstream of the plasma generation device in the direction of flow and exactly one catalyst arrangement is located behind it. Alternatively or additionally, it is possible in one embodiment for one, several or all catalyst arrangements to be part of the plasma generating device. According to one development, the at least one catalyst arrangement has a photoactivatable catalyst, for example tungsten oxide or zinc oxide, in particular titanium dioxide TiC. Photoactivatable catalysts are also referred to as photocatalysts. Photoactivatable catalysts are activated in their catalytic property in particular by UV radiation, ie radiation with a wavelength of about 100 nm up to 400 nm, and are then also referred to as photocatalysts which can be activated by UV radiation. In other words, without the presence of UV radiation, such a photocatalyst which can be activated by UV radiation is catalytically only slightly active, in particular not at all active. Photoactivatable catalysts are usually semiconductors that are photochemically excited. Radicals are then formed on the surface of the photocatalyst, for example from water provided by atmospheric moisture or from molecular oxygen. The radicals then in turn react with the particularly organic and biological contaminants and decompose them. However, inorganic contaminants, such as nitrogen oxides, can also be converted with a photocatalyst, for example to form nitrate, and thereby preferably be detoxified.

At least one UV light source, in particular a lamp or a lamp array, is present, for example, to activate the photoactivatable catalyst. This generates UV radiation and radiates it onto the at least one catalyst arrangement.

The at least one catalyst arrangement is preferably arranged spatially in relation to the gap in such a way that at least part of the UV radiation produced during the plasma discharge impinges on the at least one catalyst arrangement and activates the photoactivatable catalyst.

During plasma generation, UV radiation is inevitably produced, which has a small share in the disinfecting effect of a plasma, but apart from that it is more likely to be regarded as a waste product during plasma generation.

According to the development of the invention, this can now be used to activate the photoactivatable catalyst. For this purpose, the at least one catalyst arrangement is spatially arranged in relation to the gap in such a way that at least part of the UV radiation generated during plasma generation radiates directly onto the at least one catalyst arrangement. The plasma generating device is preferably sufficient to activate the photoactivatable catalyst or at least to support this significantly. At least 10%, in particular at least 25%, of the UV radiation produced during plasma generation preferably radiates directly onto the at least one catalyst arrangement.

It is also possible within the scope of the invention for light-guiding devices and/or reflectors to be present, which alternatively or additionally direct UV radiation onto the at least one catalytic converter arrangement. This consequently does not radiate, or not only directly, onto the at least one catalytic converter arrangement, but is diverted onto them via the light guide devices and/or reflectors. The at least one catalyst arrangement is in particular also arranged in such a way that at least part of the UV radiation produced during the plasma discharge impinges on the at least one catalyst arrangement and activates the photoactivatable catalyst when no direct UV radiation from the plasma generated impinges on the catalyst arrangement, but the UV radiation is directed onto them exclusively via devices such as light guide devices and/or reflectors.

It is of course possible for the catalyst arrangements to be designed differently and for example not all to have a photoactivatable catalyst. It is of course possible, but not necessary, for those catalyst arrangements which do not have a photoactivatable catalyst to also be irradiated with UV radiation.

If the UV radiation that occurs anyway during plasma generation is used at the same time to activate the photoactivatable catalyst, an additional UV radiation source can be dimensioned smaller or can even be omitted entirely.

At least one electrode of the plasma generating device is preferably arranged on the support of the at least one catalyst arrangement and/or is designed as part of the support. This means that the respective catalyst arrangement is designed as part of the plasma generating device, since its carrier provides at least one electrode. In this way, it is consequently possible for the wearer to have two tasks accomplished at the same time. On the one hand, it carries the at least one catalyst and, on the other hand, provides at least one electrode.

The carrier is preferably designed entirely as an electrode. According to one embodiment, the electrode arranged on the carrier or in particular formed by the carrier is provided and designed as a ground electrode. For this purpose, it is preferably not embedded in a dielectric. However, it is also possible that the electrode is not embedded in a dielectric, although it is connected to an AC voltage source and is therefore not intended as a ground electrode. It is then preferably ensured by a housing and/or the geometry of the carrier that contact between the electrode and a person during operation is ruled out or at least made sufficiently difficult.

According to a further embodiment, the electrode arranged on the carrier or in particular formed by the carrier is embedded in a dielectric and connected to an AC voltage source. If the electrode is formed by the carrier itself, the at least one catalyst is applied to the dielectric.

According to a preferred embodiment, there are two catalytic converter arrangements, both of which are part of the plasma generation device and preferably both have a carrier which is designed as an electrode. At least one further electrode, which is also referred to as the middle electrode, is preferably located in the direction of flow between the two catalyst arrangements. A plasma is then generated between this central electrode and the two other electrodes during operation.

Because the at least one catalyst arrangement is part of the plasma generating device, a spatially particularly close proximity between the at least one catalyst on the one hand and the plasma generated in the gap on the other hand is possible. This facilitates or improves the activation of the preferably present photoactivatable catalyst by the radiation produced during plasma generation, in particular UV radiation. The carrier has through openings through which the gas to be cleaned flows during operation. According to a preferred embodiment, the central electrode extends at least in regions into the through-openings. For this purpose, the central electrode preferably has projections that extend into the through-openings. The through-openings are preferably configured in a honeycomb shape. This makes it possible for the plasma to form in the passage opening of the at least one carrier designed as an electrode. The gap is then formed particularly continuously between the wall of the through-holes on the one hand and the respective projection. In this embodiment, the catalytic and plasmatic treatment of the gas to be cleaned consequently takes place at least partially simultaneously.

The gas purification device preferably has no additional light source set up to activate the photoactivatable catalyst. In particular, the gas purification device has no additional UV radiation source. The photoactivatable catalyst is therefore activated in particular completely by means of the UV radiation produced during plasma generation. Naturally, small amounts of UV light incident from outside are unaffected by this.

The at least one catalyst arrangement preferably has a low-temperature catalyst, for example nickel oxide or cerium oxide, in particular manganese monoxide MnO and/or an adsorbent, for example activated carbon or activated coke, in particular a zeolite. These are preferably in powder form.

A low-temperature catalytic converter is a catalytic converter that is already catalytically active at low temperatures. A low-temperature catalyst preferably already exhibits its catalytic activity at temperatures below 100.degree. C., preferably below 50.degree. C., particularly preferably even at room temperature, ie 20.degree. In particular, however, it cannot be ruled out that the catalytic activity of a low-temperature catalyst increases as the temperature rises.

The manganese monoxide MnO is preferably at most 10% by weight, more preferably at most 5%, particularly preferably at most 1% by weight with manganese dioxide MnO2 contaminated. In the best case, the manganese monoxide is completely free of manganese dioxide MnÜ2.

The zeolite is preferably a hydrophilic zeolite, in particular of type A and/or Y. The zeolite is preferably produced synthetically.

The electrodes are preferably designed as plate electrodes or as electrodes which mesh with one another.

The electrodes are spaced apart so that a gap is formed between them. This gap is preferably homogeneous, so that the electrodes always have the same distance from one another, which always means the minimum distance between the electrodes. However, this is not necessary. The distance and thus in particular the thickness of the gap is preferably at least 2 mm, in particular at least 5 mm, particularly preferably at least 10 mm. The gap preferably has a thickness of at most 20 mm, in particular at most 15 mm.

In the case of the plate electrodes, these are preferably parallel to one another and thus form a homogeneous gap. Plate electrodes are not necessarily entirely plate-shaped. It is also possible and preferred that the electrode has a more complex geometry and forms an electrode plate only at one end, which then delimits the gap on one side. For example, the electrode can have an electrode plate, on the back of which a rod-shaped part of the electrode is arranged, via which the electrode is preferably electrically contacted.

The intermeshing electrodes form a meandering gap, which is delimited on both sides by an electrode. The electrodes thus interlock but do not touch. For this purpose, both electrodes are configured in a comb-like manner, for example in the plan view, ie they each have projections protruding forwards. Every two projections of one electrode form an intermediate space in between, into which a projection of the other electrode extends. The projections are preferably plate-shaped. These electrodes are preferably designed and arranged in such a way that that the meandering gap always has the same thickness, that is, the electrodes always have the same distance from one another. With this type of electrode, a large contact area between gas and electrodes can be provided in the gap in a relatively compact space. At the same time, a correspondingly large volume flow per unit of time can flow through the gap and be cleaned. The thickness of the gap in the case of the electrodes which engage in one another in a meshing manner can therefore preferably be selected to be smaller than in the case of plate electrodes for the same installation space.

The electrode material is, for example, a metal or preferably an electrically conductive, doped silicone. The dielectric is preferably a silicone that is not doped and is therefore electrically insulating. Alternatively, the dielectric can also be a ceramic material or a plastic.

At least one of the electrodes is connected to an AC voltage source, which is preferably part of the gas purification device. If only one electrode is connected to an AC voltage source, the other electrode is preferably designed as a ground electrode. The ground electrode is therefore in particular grounded or at least has a lower electrical potential than the other electrode, which can also be referred to as the high-voltage electrode.

It is also possible for both electrodes to be connected to an AC voltage source and to have an AC voltage applied to them simultaneously during operation. The AC voltage applied to one electrode then preferably has a phase shift of 180° in relation to the AC voltage applied to the other electrode.

The AC voltage source is set up in particular to provide voltage and frequency in such a way that a plasma is generated in the gap for a given electrode geometry and thickness of the gap.

Gas baffle plates are preferably arranged upstream of the plasma generating device in the direction of flow, which narrow the cross section that can be flowed through and direct the gas to the plasma generating device. In this embodiment, there is a larger cross-section through which flow can take place in front of the gas baffles. This can for example only be specified by the wall of the housing. The gas baffles narrow the cross-section that can be flowed through and direct the gas to be cleaned to the plasma generating device. This preferably does not extend over the entire cross section of the housing, but only over part of it. For this purpose, the dimensions of the narrowed cross section are preferably matched to the size of the plasma generating device.

The gas baffle plates form an inflow opening which, in particular, has the full cross section of the housing. They then run in such a way that they narrow the cross section through which flow can take place. On the side opposite the inflow opening, the gas guide plates form an outflow opening which, for example, has a smaller cross section than the inflow opening. This is particularly the case when the plasma generating device does not extend over the entire cross section of the housing. It is also possible and the subject of a further embodiment that the inflow opening and the outflow opening have the same cross section, ie there is no constriction. This is particularly advantageous when the plasma generating device extends over an area that already corresponds to the cross section of the inflow opening, so that no constriction is necessary.

A catalyst arrangement is preferably arranged between the gas baffle plates. If the gas baffle plates narrow the cross section through which flow can take place, the catalytic converter arrangement is preferably arranged where the cross section through which flow can take place is smallest. In addition, the catalyst arrangement is preferably arranged as close as possible to the outflow opening, so that the distance between the plasma generating device and the catalyst arrangement is as small as possible. This is advantageous when the catalyst arrangement has a photoactivatable catalyst, which then reaches as much of the UV radiation produced during plasma generation as possible due to the physical proximity. In one embodiment, behind the outflow opening and in particular behind the plasma generating device, the cross section through which the flow can pass is enlarged again, in particular identical to the cross section in the direction of flow in front of the gas baffle plates.

Behind the plasma generation device there is preferably an additional catalytic converter arrangement which extends in particular over the entire cross-section through which flow can take place.

According to a further development, a pre-filter is arranged upstream of the at least one catalyst arrangement and the plasma generation device and/or a post-filter is arranged downstream of the at least one catalyst arrangement and the plasma generation device.

The pre-filter can be, for example, a particularly replaceable particle filter, which frees the gas to be cleaned from the smallest particles, but also at least partially from biological contaminants such as bacteria or viruses. In this way, at least coarse contaminants, which could otherwise possibly exceed the cleaning capacity of the device or damage components, can be filtered out. According to a preferred embodiment, the pre-filter is designed in such a way that it largely allows biological contaminants such as bacteria and viruses to pass through and only retains larger particulate contaminants. In this way, it is possible to largely or almost completely not catch the biological contaminants in the pre-filter, but to direct them to destruction by the catalyst and/or plasma.

The pre-filter is preferably arranged in front of the other components, ie in particular the catalytic converter arrangements, the plasma generation device and, if necessary, the intake device. The pre-filter can be assigned to the inlet opening in the gas purification device.

Alternatively or additionally, an after-filter is preferably present, which is arranged behind all catalytic converter arrangements and the plasma generating device. This is designed, for example, as an activated carbon filter and is still in the gas to remove any impurities present. These can, for example, be degradation products as a result of the catalytic or plasma-caused degradation of other contaminants.

According to a further aspect, the invention achieves the object by a method for cleaning a gas using a gas cleaning device according to one of the preceding claims, with the steps: a) applying an AC voltage to at least one of the two electrodes of the plasma generating device, so that a plasma is generated in the gap and b) passing the gas through the gap of the plasma generating device and the at least one catalyst assembly.

Consequently, the gas to be cleaned, in particular air, is partially ionized in the plasma generating device and converted into the plasma state. As a result, impurities in the gas are at least partially broken down. In front of and/or behind the plasma generating device, the gas to be cleaned also flows along a catalyst arrangement, in particular through it, so that impurities in the gas to be cleaned are catalytically decomposed.

The cleaned gas is then preferably put to use. If it is air, for example, it is sent to a room with special requirements for the quality of indoor air. Such rooms can be, for example, operating theaters or rooms in which many people are in a small space, for example in airplanes or the like. The air in quarantine stations or in quarantine units can also be treated by means of the device according to the invention and the method according to the invention and can thus be supplied to the environment without or only with a significantly lower risk of infection. Especially today, under the impression of the COVID-19 pandemic, it makes sense and is important to create effective air cleaning devices, on the one hand to clean the room air in rooms with many people or a lot of public traffic, and on the other hand to clean the air from quarantine units safely, in order to then feed them into the environment without hesitation. According to a further aspect, the device according to the invention and the method according to the invention also expressly relate to the removal of the so-called coronavirus Sars-CoV-2 from the air. According to one development, the at least one catalyst arrangement has a photoactivatable catalyst, for example tungsten oxide or zinc oxide, in particular titanium dioxide TiC, and at least part of the UV radiation produced during plasma generation is directed to the at least one catalyst arrangement, so that the photoactivatable catalyst is activated .

With this configuration of the method, the UV radiation produced during plasma generation can be put to meaningful use. It is therefore possible to provide fewer separate UV radiation sources. Preferably, no separate UV radiation source is necessary or present at all.

The at least one catalyst arrangement is preferably arranged spatially in relation to the gap in such a way that the UV radiation reaches the at least one catalyst arrangement directly. Alternatively or additionally, it is possible to redirect UV radiation in a targeted manner via light guide devices and/or reflectors and thereby direct it to the at least one catalytic converter arrangement.

The invention is explained in more detail below with reference to the accompanying figures. Show it:

Figure 1 shows a sectional view of a first embodiment of the gas cleaning device,

FIG. 2 shows an enlarged detail from FIG. 1,

Figure 3 shows another sectional view of the first embodiment,

FIG. 4 shows an enlarged detail from FIG. 3,

Figure 5 is a perspective view of the first embodiment,

FIG. 6 shows a sectional view of a second embodiment of the gas purification device,

FIG. 7 shows a sectional illustration of a third embodiment of the gas purification device,

FIG. 8 shows an enlarged detail from FIG. 7,

FIG. 9 shows a further sectional illustration of the third embodiment,

FIG. 10 shows an enlarged detail from FIG. 9,

Figure 11 is a perspective view of the third embodiment,

Figure 12 is a perspective view of a fourth embodiment of the

gas purification device,

FIG. 13 shows a sectional view of a fifth embodiment of the gas purification device, FIG. 14 shows an enlarged detail from FIG. 13,

FIG. 15 shows a sectional illustration of a sixth embodiment of the gas purification device,

FIG. 16 shows an enlarged detail from FIG. 15,

FIG. 17 shows a sectional illustration of a seventh embodiment of the gas purification device,

FIG. 18 shows an enlarged detail from FIG. 17,

FIG. 19 shows a sectional illustration of an eighth embodiment of the gas purification device, and

Figure 20 shows an enlarged detail from Figure 19.

1 shows a schematic longitudinal section along the section plane A-A shown in FIG. 3 through a first embodiment of the gas purification device 2. This has a plasma generating device 4 with two electrodes 6, between which a gap 8 (not visible in FIG. 1) is formed. Both electrodes 6 are each embedded in a dielectric 10 which almost completely encloses the electrodes 6 . The dielectric 10 is preferably only interrupted where the electrode 6 is electrically contacted or has a connection for such contacting. The surface of this electrode 6 facing the gap 8 is accordingly completely covered by the dielectric 10 . The dielectric 10 is preferably an electrically non-conductive silicone. In the present case, the electrodes 6 are designed as intermeshing electrodes, which can be seen more clearly in FIGS.

A first catalytic converter arrangement 12 is arranged upstream of the plasma generating device 4 in the direction of flow S of the gas to be cleaned. A second catalytic converter arrangement 12 is arranged downstream of the plasma generating device 4 in the direction of flow S. The catalyst assemblies 12 preferably have a carrier 13, not designated separately, which can be, for example, an aluminum sheet in the form of a honeycomb, on which at least one catalyst is located. The gas to be cleaned can flow through the honeycomb along the at least one catalytic converter, so that impurities in the gas are catalytically broken down.

The first catalyst arrangement 12 is arranged between gas baffles 14, which narrow the flow-through cross-section Baren. In the present case, the gas baffle plates 14 are arranged to form a hood and form an inflow opening 16 and an outflow opening 18 which has a smaller cross section than the inflow opening 16 .

The cross section of the inflow opening 16 essentially corresponds to the cross section of the housing 20 of the gas purification device 4. However, this is not absolutely necessary.

A pre-filter 22 and an intake device 24 in the form of a fan are arranged upstream of the plasma generating device 4 and the catalytic converter arrangements 12 in the direction of flow S.

The pre-filter 22, which is preferably a filter for suspended matter, serves in particular to remove or reduce particulate contaminants.

The suction device 24 serves to suck a gas to be cleaned along the flow direction S into the gas cleaning device 2 and to let it flow through it. The gas enters the gas purification device 4 through at least one inlet opening 26 , flows through it in the direction of flow S and exits it again through at least one outlet opening 28 . It flows through the catalyst arrangements 12 and the gap 8 of the plasma generating device.

In the direction of flow S behind the second catalytic converter arrangement 12 is an after-filter

30 arranged. This serves to remove any remaining impurities or Degradation products of previously existing and catalytically and/or plasmatically destroyed

pick up impurities. It is designed, for example, as an activated carbon filter.

In the embodiment shown in FIG. 1, each electrode 6 is assigned an AC voltage source 32, which in the present case is designed as a component. These are each connected to the electrodes 6 via electrical lines 34 .

In FIG. 1, the course of the voltage over time is indicated. It can be seen that these are 180° out of phase with each other, which is preferred.

FIG. 2 shows an enlarged detail from FIG. 1, which is indicated there by the circle labeled A. If the following features are the same as previous figures, no repetitions are made and reference is made to the previous statements on the respective features.

It can be seen more clearly in FIG. 2 that the electrodes 6 are each embedded in a dielectric 10 .

The catalyst arrangements 12 are arranged spatially close to the plasma generating device 4, which is particularly advantageous when at least one, in particular both, catalyst arrangements have a photoactivatable catalyst. The UV radiation produced during plasma generation can then radiate directly onto the catalyst arrangements and activate the photoactivatable catalyst there. It is possible, but preferably not necessary, for additional light sources to be present to activate the photoactivatable catalyst.

FIG. 3 shows a schematic sectional representation along the sectional plane B-B shown in FIG.

It can be seen that the electrodes 6 of the plasma generation device 4 mesh with one another. However, they do not touch, but rather form a gap 8 that runs in a meandering pattern. In addition, the gas baffles 14 can be seen, which form the outflow opening 18 below the plasma generating device 4 . Gas is conducted through this to the plasma generating device 4 and through the gap 8 during operation. During operation, the gas is then partially ionized in the gap 8 as a result of the alternating voltage present and is thus converted into the plasma state.

FIG. 4 shows an enlarged detail from FIG. 3, which is indicated there by the circle labeled B.

It can be seen more clearly that the two electrodes 6 form a meandering gap 8 and are each embedded in a dielectric 10 .

The two electrodes 6 are preferably of identical design, with at least one electrode 6, in particular both electrodes 6, being provided with a dielectric 10 which, in the mounted state, covers the surface facing the gap 8.

FIG. 5 shows a perspective and schematic view of the gas cleaning device 2 according to FIGS. 1 to 4. The front side of the housing 20 has not been shown in the illustration in order to see the interior of the gas cleaning device 2 . The front and/or one or more other sides are preferably removable, so that maintenance or repair work is easily possible.

It is easy to see that the gas baffles 14 form a hood. The first catalytic converter arrangement 12, which is therefore not visible in FIG. 5, is arranged inside this.

FIG. 6 shows a second embodiment of the gas purification device 2, which differs from the first embodiment shown in FIGS The electrode 6 shown on the left is provided as a ground electrode and is connected to ground 36 via an electrical line 34 . It is therefore grounded or at least has a lower electrical potential than the electrode 6 connected to the AC voltage source 32, which is also referred to as the high-voltage electrode can be. In this specific embodiment, it is possible in particular for only the one electrode 6 connected to the alternating current source to be embedded in a dielectric 10 . In particular, this can be dispensed with in the case of the ground electrode, since this does not have any dangerous potential during operation. Nevertheless, it is also possible in this embodiment for both electrodes 6 to be embedded in a dielectric 10 since the electrodes are preferably of identical design and therefore only one type of electrode has to be used and kept available.

FIG. 7 shows a schematic sectional illustration along the sectional plane A-A shown in FIG. 9 of a third embodiment of the gas purification device 2, in which the electrodes 6 are designed as plate electrodes. As can be seen, however, this does not mean that the electrodes 6 are completely plate-shaped. Rather, the electrodes 6 are rod-shaped and have a plate-shaped extension at their ends facing the gap 8 . The electrodes 6 are each almost completely embedded in a dielectric 10 so that both electrodes 6 have a dielectric 10 on their surfaces facing the gap 8 .

It can be seen that the cross section of the outflow opening 18 is smaller than in the embodiments according to FIGS. In this way it is ensured that the largest possible proportion of the gas to be cleaned is actually passed through the gap 8 in order to subject it to cleaning by the plasma generation.

In the present embodiment, both electrodes 6 are supplied with an AC voltage from an AC voltage source 32 via electrical lines 34 . This is, as preferred and also previously described, phase-shifted by 180° between the two electrodes 6 .

Regardless of the embodiment, the voltage to be applied is preferably dependent, among other things, on the thickness of the gap 8, the electrical den 6, the dielectric 10 used and the gas to be cleaned are selected in such a way that the gas flowing through the gap is converted into the plasma state.

FIG. 8 shows an enlarged detail from FIG. 7, which is indicated there by the circle labeled A.

The electrodes 6 designed as plate electrodes can be seen, which are each embedded in a dielectric 10 .

The catalyst arrangements 12 are arranged spatially close to the plasma generating device 4, which is particularly advantageous if at least one, in particular both, catalyst arrangements 12 have a photoactivatable catalyst. The UV radiation produced during plasma generation can then radiate directly onto the catalyst arrangements 12 and activate the photoactivatable catalyst there. It is possible, but preferably not necessary, for additional light sources to be present to activate the photoactivatable catalyst.

FIG. 9 shows a schematic sectional representation along the sectional plane B-B shown in FIG.

The electrodes 6 embodied as plate electrodes are arranged above the outflow opening 18 (not designated) of the gas baffles 14 . During operation, the gas thus flows almost completely through the gap 8 formed by the two electrodes 6 .

FIG. 10 shows an enlarged detail from FIG. 9, which is indicated there by the circle labeled B.

FIG. 11 is a perspective and schematic view of the gas cleaning device 2 according to FIGS. The front and/or one or more other sides are preferably removable, so that maintenance or repair work is easily possible. It is easy to see that the gas baffles 14 form a hood. The first catalytic converter arrangement 12, which is therefore not visible in FIG. 11, is arranged inside this.

The electrodes 6 shown are each embedded in a non-designated dielectric 10 and are supplied with alternating voltage via electrical lines 34 . For electrical contacting, the dielectric 10 is interrupted and, for example, pierced through a connection socket.

FIG. 12 shows a fourth embodiment of the gas cleaning device 2, which differs from the third embodiment shown in FIGS The electrode 6 shown on the left is provided as a ground electrode and is connected to ground 36 via an electrical line 34 . It is therefore grounded or at least has a lower electrical potential than the electrode 6 connected to the AC voltage source 32, which can also be referred to as the high-voltage electrode.

In accordance with the statements relating to FIG. 6, it is also possible in this embodiment, but not necessary, to dispense with the embedding of the electrode 6 provided as the ground electrode in a dielectric 10.

FIG. 13 shows a fifth embodiment of the gas cleaning device 2 in which the catalyst arrangements 12 are designed as part of the plasma generating device 4 . They each have a carrier 13 which is designed as an electrode 6 of the plasma cleaning device 4 . The carrier 13 and thus the respective electrode 6 can each be flowed through in the flow direction S and are in the present case designed in a honeycomb manner. The supports 13 are each coated with at least one catalyst, in particular a mixture of a photoactivatable catalyst, a low-temperature catalyst and an adsorbent. In addition, a further electrode 6 , also referred to as the middle electrode, of the plasma generating device 4 is arranged in the direction of flow S between the catalyst arrangements 12 . This is also designed so that it can be flowed through in the flow direction S and is designed, for example, in the form of a grid, in particular as a perforated plate or as expanded metal.

The supports 13 embodied as electrodes 6 are provided as ground electrodes in the present case and are connected to ground 36 via an electrical line 34 . Therefore, the carriers 13 designed as electrodes 6 are not embedded in a dielectric 10 in the present case. However, this is not mandatory. The middle electrode 6 is embedded in a dielectric and connected to an AC voltage source 32 via an electrical line 34 . Both can be seen more clearly in FIG.

It can also be seen in FIG. 13 that the plasma generating device 4 and the catalyst arrangements 12 extend over the entire cross section of the housing 20 and insofar as no separate gas baffles 14 are present. According to an alternative embodiment, however, they do not extend over the entire cross section and corresponding gas baffle plates 14 are present.

FIG. 14 shows an enlarged detail from FIG. 13, which is indicated there by the circle labeled A.

It can be seen more clearly that the carriers 13 are in the form of electrodes 6 , which are not embedded in a dielectric 10 . The supports 13 form a plurality of passage openings 38 through which the gas to be cleaned flows during operation along the at least one catalytic converter.

The middle electrode 6, which is embedded in a dielectric 10, also has passage openings 40 through which the gas to be cleaned flows during operation. During operation, the plasma is then generated in the gap 8 in each case between the carriers 13 and the central electrode 6 . FIG. 15 shows an embodiment of the gas purification device 2 which essentially corresponds to the embodiment from FIG. However, both carriers 13 designed as electrodes 6 are each connected to an AC voltage source 32, the AC voltages being phase-shifted by 180°, as is preferred and indicated in FIG. Correspondingly, the carriers 13 are embedded in a dielectric 10 . However, this is not absolutely necessary and can be omitted in particular if a housing and/or the geometry ensures that no contact with a person is possible during operation or that this is at least made sufficiently difficult.

In this embodiment, the at least one catalyst, in particular the mixture of a photoactivatable catalyst, a low-temperature catalyst and an adsorbent, is not applied directly to the carrier 13, but rather to the dielectric 10 embedding it.

FIG. 16 shows an enlarged detail from FIG. 15, which is indicated there by the circle labeled B. It can be seen more clearly that all electrodes 6 are each embedded in a dielectric 10 .

FIG. 17 shows a further embodiment of the gas purification device 2, in which the central electrode 6 extends in some areas into the through-openings 38 of the supports 13 designed as electrodes 6. In this embodiment, the supports 13 designed as electrodes 6 are provided as ground electrodes, as in the embodiment according to FIG. 13, and are therefore not embedded in a dielectric 10, as is preferred. The middle electrode is connected to an AC voltage source 32 and embedded in a dielectric 10 .

FIG. 18 shows an enlarged detail from FIG. 17, which is indicated there by the circle labeled C. It can be seen that the middle electrode 6 has rod-shaped projections 42 which extend into the through-openings 38 . It can be seen that the electrodes 6 terminate flush with the carriers 13, as is preferred. Only the embedding dielectric 10 protrudes beyond the carrier 13 . Protrusions 42 can also be seen in FIG. which are offset to the projections 42 lying in the plane of the paper behind the plane of the paper and extend into through-openings 38 there. As a result, a circumferential gap 8 is formed in the through openings 38 between the carrier 13 and the projections 42, in which a plasma is generated during operation.

The middle electrode 6 also has passage openings 40 through which flow can take place in the direction of flow S, but these are not shown in FIG. These are in front of and behind the plane of the paper.

FIG. 19 shows an embodiment of the gas purification device 2 which essentially corresponds to the embodiment from FIG. However, both carriers 13 designed as electrodes 6 are each connected to an AC voltage source 32, the AC voltages being phase-shifted by 180°, as is preferred and indicated in FIG. Correspondingly, the carriers 13 are embedded in a dielectric 10 . However, this is not absolutely necessary and can be omitted in particular if a housing and/or the geometry ensures that no contact with a person is possible during operation or that this is at least made sufficiently difficult.

FIG. 20 shows an enlarged detail from FIG. 19, which is indicated there by the circle labeled D. This shows more clearly that all electrodes 6 are embedded in a dielectric 10 . In this embodiment, therefore, the projections 42 are preferably flush with the carriers 13 .

Reference List

2 gas cleaning device

4 plasma generating device

6 electrode

8 column

10 dielectric

12 Catalyst Assembly

13 carriers

14 gas baffle

16 inflow opening

18 outflow opening

20 housing

22 pre-filters

24 suction device

26 inlet opening

28 drain hole

30 post filters

32 AC power source

34 electric line

36 grounding

38 passage opening of the carrier

40 center electrode through hole

42 projection

Claims

29 patent claims:

1. Gas cleaning device (2) for cleaning a gas, with at least one catalyst arrangement (12), characterized in that the gas cleaning device has a) a plasma generating device (4) for generating a plasma, the plasma generating device (4) having at least two electrodes (6) between which at least one gap (8) is formed, in which the plasma generation takes place, and b) the plasma generating device (4) and the at least one catalyst arrangement (12) are arranged and set up in such a way that the gas to be cleaned during operation of the gas cleaning device (2) flows through the gap (8) and the at least one catalyst arrangement (12) and the at least one catalyst device is arranged upstream and/or downstream of the plasma generating device (4) in the direction of flow (S) of the gas to be cleaned and/or as part of the plasma generating device (4) is formed.

2. Gas cleaning device (2) according to claim 1, characterized in that the plasma generating device (4) is designed to generate a dielectric barrier plasma discharge and at least one of the electrodes (6) has a dielectric (10) at least on its surface facing the gap (8). having.

3. Gas purification device (2) according to any one of claims 1 or 2, characterized in that the at least one catalyst arrangement (12) has a photoactivatable catalyst. 30

4. Gas cleaning device (2) according to claim 3, characterized in that the at least one catalyst arrangement (12) is arranged spatially to the gap (8) in such a way that at least part of the UV radiation produced during the plasma discharge is incident on the at least one catalyst arrangement ( 12) and activates the photoactivatable catalyst.

5. Gas purification device (2) according to one of the preceding claims, characterized in that at least one electrode (6) is arranged on a carrier (13) of the at least one catalyst arrangement (12) and/or is designed as part of the carrier (13).

6. Gas cleaning device (2) according to any one of the preceding claims, characterized in that it has no additional UV radiation source.

7. Gas purification device (2) according to one of the preceding claims, characterized in that the at least one catalyst arrangement (12) has a low-temperature catalyst and/or an adsorbent.

8. Gas purification device (2) according to any one of the preceding claims, characterized in that the electrodes (6) are designed as plate electrodes or as intermeshing electrodes.

9. Method for cleaning a gas by means of a gas cleaning device (2) according to one of the preceding claims, with the steps: a) applying an AC voltage to at least one of the two electrodes (6) of the plasma generating device (4), so that in the gap (8) a plasma is generated, and b) conducting the gas through the gap (8) of the plasma generating device (4) and the at least one catalyst arrangement (12).

10. The method according to claim 9, characterized in that the at least one catalyst arrangement (12) has a photoactivatable catalyst, in particular titanium dioxide TiÜ2, and at least a part of the plasma generation resulting UV radiation reaches the at least one catalyst arrangement (12), so that the UV-radiation-activatable catalyst is activated.