EP1285153B1 - Particulate trap - Google Patents

Description

The invention relates to a particulate trap for a particle-laden fluid, in particular for the exhaust gas of a diesel engine, wherein the particulate trap is regenerable by oxidation of the particles and into a tube, such as. in the exhaust system of a motor vehicle, can be installed.

A fluid, e.g. the exhaust gas of a motor vehicle, contains in addition to gaseous components and particles. These are expelled with the exhaust gas or possibly accumulate in the exhaust system and / or in a catalytic converter of a motor vehicle. With load changes they are then in the form of a particle cloud, such as. a soot cloud, expelled. For filtering these particles different systems are known.

From the DE 4206812 A1 For example, a filter is known which comprises a net-like perforated metal plate. The filter is made up of several smooth and wavy layers. The US 4,597,262 discloses a catalyst for a diesel engine formed from a stack of smooth sheets having indicia that space adjacent sheets apart and redirect flow. DE 33 41 177 A1 discloses a filter formed of concentric cylindrical hole sieves. EP 0 244 798 A1 discloses the structure of a filter made of folded metal layers, similar DE 298 21 009 U1 ,

WO 97/49905 discloses a catalyst having a corrugated honeycomb body with a plurality of structures protruding from the corrugations. WO 90/12950 discloses a particulate trap having a honeycomb body constructed of spirally unfurled, alternating smooth and corrugated sheet metal layers and having turbulence-promoting noses.

Traditionally, sieves (sometimes referred to as filters) are used to trap the particles. However, the use of the sieves has two significant disadvantages, on the one hand they can clog and on the other hand they cause an undesirably high pressure drop. In addition, legal values for motor vehicle emissions must be complied with, which would be exceeded without particle reduction. There is therefore a need to provide catch elements for exhaust particles which overcome the disadvantages of screens, filters or other systems.

The object of the invention is to provide a particle trap for a fluid flow that is regenerable and open.

The invention relates to a particle trap with flow channels and structures in order to Fluid flow passing through the particulate trap to create turbulence, settling and / or dead zones, wherein the particulate trap is at least partially open and at least a portion of the flow channels at least a portion having an increased heat capacity due to a thicker channel wall, so that in dynamic Load changes with rapidly increasing fluid temperature for particles entrained in the fluid, the effect of thermophoresis in these areas increasingly occurs. In addition, various uses of the particulate trap in various combinations with other modules are the subject of the invention. The particles according to the invention have channel walls which are at least partially constructed from at least one corrugated layer. The channel walls widen structures which generate Nerwirbelungs-, sedation and / or Torzonen in the fluid flow.

In experiments with mixing elements made of metal foils, as used for example in the WO91 / 01807 or the WO91 / 01178 described and have been tested for better distribution of injected in exhaust systems additives, it has surprisingly been successful on the bare, ie uncoated metal of the films particles, such as the soot from a diesel engine, deposit and bring to oxidation.

The particles are probably thrown by turbulences to the inner walls of the channels and adhere there. The turbulences are created by structures of the channel insides, which structures not only create turbulence, but also calming or dead zones in the flow shadow. In the calming and / or dead zones, the particles are presumably washed up (comparable to gravitational separation) and then adhere firmly. In the adhesion of the particles, a possible interaction metal soot and / or the temperature gradient fluid / channel wall plays a role. It is also observed a strong agglomeration of the particles in the gas stream or on the walls.

The calming zone is a zone in the low flow channel and the dead zone is a zone without fluid movement.

In contrast to closed systems, the particulate trap is referred to as "open" because no flow-back alleys are provided. This property can also be used in the case for characterizing the particle trap, such as an openness of 20% means that in a cross-sectional view about 20% of the surface can be freely flowed through. With a carrier having 0.93 cells per mm ² (600 cpsi (cells per square inch)) with a hydraulic diameter of the channels of about 0.8 mm would correspond to an area of about 0.01 mm ^2.

The particulate trap does not clog like a conventional filtration system where pores can become clogged because previously the flow would entrain the portion of the agglomerated particles which can rupture due to its increased air resistance.

To produce a particle trap, at least partially structured layers are layered or wound by known methods and joined by joining, in particular soldered. The cell density of the particle trap depends on the corrugation of the layers. The corrugation of the layers is not necessarily uniform over an entire layer, but different flows and / or pressure conditions within the traversed particle trap can be produced by suitable production of the layer structure.

The particulate trap can be monolithic or multiple slices, that is to say composed of one or more individual elements connected in series.

To cover various (dynamic) load cases of the drive system of a motor vehicle, a system with conical channels or a cone-shaped element is preferred. Such systems, such as in the WO93 / 20339 described, have expanding or narrowing channels, so that at any mass flow at any point of the channels, if they are with appropriate Deflection or turbulence structures are provided, particularly favorable conditions for the collection of particles arise.

Cone-shaped designates both the designs that show an increase in diameter in the flow direction as well as the designs that have a diameter reduction. Also cylindrical honeycomb body with channels, part of which narrows and a part widened have suitable properties.

According to one embodiment of the invention of several layers wound into a honeycomb body, a smooth layer lying between two corrugations has holes, so that a fluid exchange between the channels formed by the winding is possible. As a result, a radial flow through the particle trap, which is not bound to a 90 ° deflection, possible. In the embodiment of the smooth layer with holes, these are preferably located at the outlet of flow guide vanes, so that the flow is passed directly into the holes. Instead of the smooth layer with holes, another penetrable material, such as e.g. a fiber material can be used.

The material of the layers is preferably metal (sheet), but it can also be a substance of inorganic (ceramic, fiber material), organic or organometallic nature and / or a sintered material, as long as it has a surface on which without coating, the adhesion of the particles succeed.

The particle trap in use is subject to large temperature fluctuations in a partially oxidative atmosphere (air), and arise at the surface of the layers, if they are made of metal, various oxides, possibly even in the form of acicular crystals, so-called whiskers, which cause a certain surface roughness. The particles of the flow, which basically behave in a similar way to molecules, become through different mechanisms, in particular impaction or interception in turbulent flow or laminar flow thermophores are rinsed and held at this rough surface, the adhesion being caused essentially by Van der Waals forces.

Although the deposition of the particles takes place on the uncoated metal foil is not excluded that there are also coated areas of the particulate trap, because the particulate trap is formed for example in one part as a catalyst support.

The film thickness of the layers is preferably in the range between 0.02 and 0.2 mm, particularly preferably between 0.05 and 0.08 mm, in areas with increased heat capacity preferably between 0.65 and 0.11 mm.

In the case of the particle trap with several wound layers, these are made of the same or unequal material or, if they have the same or different film thickness.

The particles in the exhaust gas of a diesel engine, which consist essentially of soot, can be charged and / or polarized by passing through an electric field, so that they are deflected by their preferred flow direction (eg axial direction of the particle trap parallel to the flow channels). Thus, the probability of the particles from hitting the walls of the flow channels of the particle trap is increased since, as they flow through the particle trap, they now also have a velocity component in another direction, in particular perpendicular to the preferred flow direction. This can be realized, for example, with a plasma trap upstream of the particle trap, which ensures polarization of the particles. It is also particularly advantageous that the particle trap forms at least one pole of the polarization path, in particular if the particle trap has at least partially a positive charge, and thus electrically negatively polarized particles are actively attracted. Such are the mechanisms by the particles are flushed out of the flow inside the wall (eg interception and impaction), accelerated and amplified.

In the event that the particulate trap is charged, it is advantageous that tips are arranged on the layers and / or in the structure of the film forming the layers, which reinforce the charging effect. The particles of the fluid can be passed, for example, through a polarization path for charging, while the particles are then polarized. However, the particulate trap can also be grounded and remain charge-neutral, in particular if suitable insulation with respect to the tips and / or the polarization path is provided.

The polarization and / or charging takes place according to an embodiment also via a photoionization.

In one embodiment, the particles are charged and / or polarized via a corona discharge.

According to one embodiment of the particulate trap, it is made use of the knowledge that a temperature difference between the channel wall and the flow serves to increase the migration of the particles to the channel wall (thermophoresis). Accordingly, a thick and thus high heat capacity equipped channel wall (caused by a corresponding film thickness of the layer in place) with opposing structures (conductive structures), which direct the particles to this wall (such as by generation of turbulence in the flow) combined , The thick duct wall has a high heat capacity and therefore maintains a temperature difference between the flow and the duct wall longer than a thin duct wall during dynamic load changes and increasing exhaust gas temperature, thus preserving the deposition-promoting effect longer than a thin duct wall. The lead structures are structures for generating turbulence, settling and dead zones and cause a forced mixing of the flow, so that particle-rich zones are brought inside the flow to the outside and vice versa. Thus, more particles contacting the walls by interception and impaction is possible, which then remain liable.

According to one embodiment, the effect of thermophoresis is exploited by connecting several particle traps in series, each with differently thick channel walls.

The cell densities of the particulate trap are preferably in the range between 0.038 to 1.55 cells per mm ² (25 to 1000 cpsi), preferably between 0.31 and 0.62 cells per mm ² (200 and 400 cpsi).

A typical particulate trap of 0.31 cells per mm ² (200 cpsi) has a volume, based on a diesel engine of about 0.2 to 1 liter per 100 kW, preferably 0.4-0.851 / 100 kW. For the geometric surface results, for example, 1.78m ² / 100kW. Compared with the volumes of conventional filters and screening systems, this is a very small volume or a very small geometric surface compared to a conventional design with about 4 m ² surface per 100 kW.

The particulate trap is regenerable, wherein in the case of soot deposition in the diesel engine exhaust system regeneration by the oxidation of the carbon black either by nitrogen dioxide (NO ₂ ) at a temperature above about 200 ° C or with air or oxygen (O ₂ ) thermally at eg Temperatures above 500 ° C or by injection of an additive (eg Cer) takes place.

The soot oxidation by means of NO ₂ , for example via the mechanism of the "continuous regeneration trap" (CRT)

C + 2NO ₂ -> CO ₂ + 2NO

requires that before the particulate trap in the exhaust line an oxidation catalyst is set, which oxidizes NO to NO ₂ in sufficient quantity. However, the ratio of the reactants also depends significantly on the Mixing of the fluids, so that depending on the configuration of the channels of the particle trap and different proportions should be used.

Particularly advantageous, the embodiment has been found in which a means for thermal regeneration of the particulate trap is provided, so that e.g. the element is at least partially electrically heated, or the element is an electrically heatable auxiliary, such as a heating catalyst, connected upstream.

In one embodiment, it is provided that an aid depending on the occupancy / the degree of filling of the particle trap is switched on or switched to regeneration, which is measured in the simplest case on the pressure loss generated by the particulate trap in the exhaust system.

According to a preferred embodiment, an oxidation catalyst upstream of the particulate trap has a lower specific heat capacity per unit volume and number of cells than the particulate trap itself. For example, the oxidation catalyst preferably has a volume of 0.5 liter, a cell number of 0.62 cells per mm ² (400 cpsi) and a film thickness of 0.05 mm, while the particle trap with the same volume and the same number of cells has a film thickness of 0.08 mm and a downstream SCR catalyst again a film thickness of 0.05 mm.

The combination of the particulate trap with at least one catalyst and a turbocharger or the combination of a particulate trap with a turbocharger is also advantageous. In this case, the particle trap arranged downstream of the turbocharger can be arranged close to the engine or in underfloor position.

The particulate trap is also used in combination with an upstream or downstream soot filter, wherein the soot filter downstream can be substantially smaller than the conventional soot filter, because it is merely intended to provide additional protection that particle emission is excluded. A filter is preferred The size 0.5m ² per 100kW diesel engine used up to a maximum of 1m ² , (in downstream filter surface, the cross-sectional area of the filter is adapted to the particle trap, both in the case of a cross-sectional constriction as well as in the case of a cross-sectional widening) whereas without particle trap filter sizes of about 4m ² per 100kW are required.

The soot filter can also be in the form of filter material installed directly before or after the storage / oxidation element, the filter material thereby being directly, e.g. via a solder joint, which can be connected to the storage / oxidation element.

1. A) Oxidationskatalysator - Turbolader - Partikelfalle, wobei die Partikelfalle motornah oder in Unterbodenposition angeordnet sein kann.
2. B) Vorkatalysator - Partikelfalle - Turbolader
3. C) Oxidationskatalysator - Turbolader - Oxidationskatalysator- Partikelfalle
4. D) Heizkatalysator - Partikelfalle 1 - Partikelfalle 2 (wobei Partikelfalle 1 und 2 gleich oder ungleich sein kann)
5. E) Partikelfalle 1- Konusöffnung des Abgasstranges - Partikelfalle 2
6. F) Additivzugabe - Partikelfalle - Hydrolysekatalysator - Reduktionskatalysator
7. G) Vorkatalysator - Oxidationskatalysator - Additivzugabe- (eventuell Rußfilter) - Partikelfalle z.B. in Konusform, ggf. mit Hydrolysebeschichtung - (eventuell Rußfilter) - (eventuell Konus zur Erhöhung des Rohrquerschnitts) Reduktionskatalysator

The following examples represent arrangements which prove the multitude of possible combinations of the particle trap with catalysts, turbochargers, soot filter and additive addition along an exhaust system of a motor vehicle:

1. A) oxidation catalyst - turbocharger - particle trap, wherein the particulate trap can be located close to the engine or in underfloor position.
2. B) Pre-catalyst - particle trap - turbocharger
3. C) Oxidation Catalyst - Turbocharger - Oxidation Catalyst Particle Trap
4. D) heating catalyst - particle trap 1 - particle trap 2 (particle trap 1 and 2 may be the same or different)
5. E) Particle trap 1- cone opening of the exhaust line - particle trap 2
6. F) additive addition - particle trap - hydrolysis catalyst - reduction catalyst
7. G) Pre-catalyst - Oxidation catalyst - Additive additive (possibly soot filter) - Particle trap eg in cone shape, if necessary with hydrolysis coating - (possibly soot filter) - (possibly cone to increase the tube cross-section) Reduction catalyst

In one embodiment, the particulate trap is used in combination with at least one catalyst. Suitable catalysts, electrocatalysts and / or precatalysts are in particular: oxidation catalyst, Heating catalyst with upstream or downstream heating disk, hydrolysis and / or reduction catalyst. Also, as the oxidation catalyst, those which oxidize NO _x (nitrous gases) to nitrogen dioxide (NO ₂ ) will be used besides those which oxidize hydrocarbons and carbon monoxide to carbon dioxide. The catalysts are, for example, tubular or conical.

Preferably, a nitrogen dioxide (NO ₂ ) storage is used in front of the particulate trap, which provides NO ₂ in sufficient quantity for the oxidation of the carbon black in the particulate trap, if necessary. This memory can be eg an activated carbon storage eg with sufficient oxygen supply.

Depending on the embodiment, the particle trap may have different coatings in partial areas, each of which causes a functionality. For example, in addition to functioning as a trap for particles, the particulate trap may have a storage, mixing, oxidation, flow distribution function and also e.g. have a function as a hydrolysis catalyst.

By using a particulate trap, deposition rates of up to 90% can be achieved.

It has been found that the deposition of particles takes place especially at the inlet and outlet surfaces of the catalysts. Therefore, according to one embodiment, the particulate trap is not used in the form of an element, but in the form of a plurality of successively connected narrow elements, as a multi-disk element. In this case, particle traps, the corrugations without structures for generating Verwirbelungs- and calming zones and with coating (ie, for example, conventional catalysts) can be used. It will be used preferably up to 10 elements. This design, referred to as a "disk array" or "disk catalyst," can be used, for example, when particle separation is desired in the range of 10 to 20% (using conventional catalysts).

The present invention proposes a particulate trap which can replace conventional filtering and screening systems and offers major advantages over these systems:

First, it can not clog and the pressure drop generated by the system does not increase as fast with the operating time as with screens, because the particles adhere outside the fluid stream, and second, it causes relatively low pressure drops because it is an open system.

Further specific embodiments and advantages of the invention will be explained with reference to the following drawing. The embodiments shown in the drawings are to be understood as specific, exemplary and particularly preferred embodiments of the invention, which are not intended to limit the invention in its meaning and spirit.

Fig. 1

eine erfindungsgemäße Partikelfalle in Form eines lagenweise aufgebauten Wabenkörpers in perspektivischer Ansicht,

Fig. 2

eine einzelne Lage mit Strukturen zur Erzeugung von Verwirbelungs-, Beruhigungs- und/oder Totzonen,

Fig. 3

eine weitere Ausführungsform der erfindungsgemäßen Partikelfalle mit einem Plasmareaktor,

Fig. 4

eine weitere Ausgestaltung der Strukturen zur Erzeugung von Verwirbelungs-, Beruhigungs- und/oder Totzonen,

Fig. 5

eine erfindungsgemäße Partikelfalle, die radial durchströmbar ist,

Fig. 6

eine Lage mit Strukturen zur Erzeugung von Verwirbelungs-, Beruhigungs- und/oder Totzonen nach Fig. 4, und

Fig. 7

eine Partikelfalle in Scheibenanordnung mit weiteren Abgasreinigungsmitteln.

They show schematically:

Fig. 1

a particle trap according to the invention in the form of a layered honeycomb body in perspective view,

Fig. 2

a single layer with structures for creating turbulence, settling and / or dead zones,

Fig. 3

a further embodiment of the particle trap according to the invention with a plasma reactor,

Fig. 4

a further embodiment of the structures for generating turbulence, sedation and / or dead zones,

Fig. 5

a particle trap according to the invention, which can be flowed through radially,

Fig. 6

a layer with structures for generating turbulence, sedation and / or dead zones according to Fig. 4, and

Fig. 7

a particle trap in a disc arrangement with further exhaust gas cleaning agents.

FIG. 1 shows a particle trap 11 according to the invention, which is constructed from metallic layers 4, 6, which has flow channels 2 through which a fluid can flow. The layers 4, 6 are formed either as a corrugated layer 4 or as a smooth layer 6. The film thickness of the layers 4, 6 is preferably in the range between 0.02 and 0.2 mm, in particular less than 0.05 mm.

FIG. 2 schematically shows a detailed view of the corrugated layer 4, which has structures 3 for generating swirling, settling and / or dead zones 5. The fluid flows along the preferred flow direction indicated by the arrow 16.

FIG. 3 shows a further embodiment of the particle trap 11 according to the invention with an upstream plasma reactor 17. The fluid or the particles contained therein are at least polarized with the plasma reactor 17, possibly even ionized, if the fluid is in the preferred flow direction (arrow 16). flows through the plasma reactor 17. The plasma reactor 17 is connected to the negative pole of a voltage source 20. The positive pole of the voltage source 20 is connected to tips 18 of the particle trap 11, which are arranged as close as possible to the axis 19, so that a deflection of the particles occurs due to van der Waalsscher forces to the central region of the particle trap 11. The formed electrostatic field can be operated with a voltage of 3 to 9 kV. The tips 18 may be electrically conductively connected to the metallic layers of the particle trap 11. FIG. 4 shows an alternative embodiment of the corrugated sheets 4.

FIG. 5 shows a particle trap which can be flowed through radially (radius 21) (arrow 16). The flow channels 2 extend from a central channel 22, which is made porous in the region of the honeycomb body 1, radially outwardly to a honeycomb body 1 surrounding, porous shell 23. The honeycomb body 1 is made of segmented or annular smooth layers 6 and 4 corrugations educated.

FIG. 6 shows a possible segmented embodiment of the corrugated sheet 4 with structures 3 for generating turbulence, settling and / or dead zones.

FIG. 7 shows a particle trap which has conical channels and which comprises a plurality of, optionally narrow, elements which are particle traps and / or catalysts. For this purpose, a plurality of honeycomb body 1, each widening conically widen or taper arranged one behind the other. Before the honeycomb bodies 1 is an additive addition 7, a nitrogen storage 14 and an oxidation catalyst 8, which nitrous gases (No _x ) are oxidized to nitrogen dioxide (NO ₂ ), upstream in the exhaust line 12. A turbocharger 9 and a soot filter 10 are connected downstream. Advantageously, the particulate trap 11 is used in combination with an aid for soot oxidation 15.

LIST OF REFERENCE NUMBERS

1

honeycombs

2

flow channel

3

structures

4

Well location

5

dead zones

6

smooth layer

7

additive addition

8th

oxidation catalyst

9

turbocharger

10

soot filter

11

particulate trap

12

exhaust gas line

13

channel wall

14

nitrogen storage

15

Auxiliary for soot oxidation

16

arrow

17

plasma reactor

18

top

19

axis

20

voltage source

21

radius

22

Central channel

23

coat

Claims (27)

1. A particle trap (11) for the agglomeration and oxidation of particles in a fluid flow, in particular in an exhaust gas flow from a motor vehicle, the particle trap (11) having a multiplicity of flow passages (2) which are substantially rectilinear and having passage walls (13), and the passage walls (13) having structures (3), so that the structures (3) generate swirling, calming and/or dead zones (5) in the fluid flow yet nevertheless ensure that the particle trap (11) is open, and is characterized in that at least some of the flow passages (2), at least in a partial region of the passage walls (13), have a high heat capacity due to thicker passage walls (13), so that when the fluid temperature rises, the effect of thermophoresis for particles which are present in the fluid flow occurs to an increased extent in this partial region.
2. Particle trap (11) as claimed in claim 1, characterized in that it (11) is designed in a form of a honeycomb body (1) which is of a layered structure, the particle trap (11) preferably being produced from only one layer.
3. Particle trap (11) as claimed in claim 2, characterized in that the particle trap (11) is composed at least in part of metallic layers (4, 6), these layers preferably having a foil thickness of 0.02 to 0.2 mm, in particular between 0.05 and 0.08 mm.
4. Particle trap (11) as claimed in claim 3, characterized in that the layers (4, 6) are at least partially blank, i.e. uncoated.
5. Particle trap (11) as claimed in one of the preceding claims, characterized in that the particle trap (11) has a cell density of 0,038 to 1,55 cells per mm² (25 to 1.000 cpsi - cells per square inch), preferably between 0,31 to 0,62 cells per mm² (200 and 400 cpsi).
6. Particle trap (11) as claimed in one of the preceding claims, in which the passage walls (13) are formed by means of metal foils with a foil thickness, characterized in that the foil thickness in the partial region of the passage walls (13) with a high heat capacity amounts to a foil thickness of between 0.65 and 0.11 mm.
7. Particle trap (11) as claimed in one of the preceding claims, which is produced from a first layer (6) and at least one further foil which may be a corrugated layer (4) or a smooth layer (6).
8. Particle trap (11) as claimed in one of the preceding claims, through which a medium can flow in the radial direction.
9. Particle trap (11) as claimed in one of the preceding claims, which has conical flow passages (2).
10. Particle trap (11) as claimed in one of the preceding claims, which comprises a plurality of (optionally narrow) elements which are particle traps (11) and/or catalytic converters (8).
11. Particle trap (11) as claimed in claim 10, which has at least two elements with different heat capacities.
12. Particle trap (11) as claimed in one of the preceding claims, in which the particle trap (11) comprises a hydrolysis coating.
13. The use of at least one particle trap (11) as claimed in one of claims 1 to 12 in an exhaust section (12) of a motor vehicle (14).
14. The use of at least one particle trap (11) as claimed in one of claims 1 to 12, in combination with at least one addition (7) of additive upstream or downstream.
15. The use of at least one particle trap (11) as claimed in one of claims 1 to 12, in combination with at least one catalytic converter (8).
16. The use of at least one particle trap (11) as claimed in one of claims 1 to 12 in combination with at least one oxidation catalytic converter (8) which is connected upstream and/or downstream and at least one of which oxidizes nitrous gases NO_x to form nitrogen dioxide NO₂.
17. The use of at least one particle trap (11) as claimed in one of claims 1 to 12, in combination with at least one upstream and/or downstream turbo charger (9), the particle trap (11) being arranged close to the engine and/or in an underbody position.
18. The use of at least one particle trap (11) as claimed in one of claims 1 to 12 in a diesel engine exhaust section in combination with an upstream or downstream turbo charger (9), upstream of which, in turn, there is at least one oxidation catalytic converter (8).
19. The use of at least one particle trap (11) as claimed in one of claims 1 to 12, for soot oxidation.
20. The use as claimed in claim 19, using nitrogen dioxide as oxidizing agent.
21. The use as claimed in claim 19 or 20, in which the particle trap (11) is used in combination with an auxiliary means for soot oxidation (15).
22. The use as claimed in one of claims 19 to 21, in combination with an upstream nitrogen dioxide store (14).
23. The use of at least one particle trap (11) as claimed in one of claims 1 to 12, in combination with an upstream or downstream soot filter (10).
24. The use of at least part of a particle trap (11) as claimed in one of claims 1 to 12, as support for a catalytically active coating.
25. The use of at least one particle trap (11) as claimed in one of claims 1 to 12 and/or of a catalytic converter in a disc arrangement.
26. The use of at least one particle trap (11) as claimed in one of claims 1 to 12 in combination with at least one device for charging/polarizing either the particles which are to be trapped and oxidized and/or the particle trap (11).
27. The use as claimed in claim 26, in which a plasma reactor (17) for polarizing the particles is connected upstream of the at least one particle trap (11), and the particle trap (11) preferably forms an electric pole.

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