Exhaust-gas cleaning device

Abstract

The present invention describes an exhaust-gas cleaning device (1, 1') for cleaning exhaust gases from fireplaces fuelled by solids, especially wood, for example. The exhaust-gas cleaning device is designed as an electrostatic particle separator, wherein the electrostatic particle separator has at least one separation chamber (15, 15'), wherein at least one first electrode (11, 11'), which is preferably designed as a discharge electrode, and a second electrode (13, 14), which is designed as a counter electrode, are arranged in the separation chamber (15, 15'), wherein the at least one first electrode (11, 11') is surrounded by the at least one second electrode (13, 14), and wherein the separation chamber (15, 15'), for the purpose of conducting through an exhaust-gas stream, in particular an exhaust-gas stream from a fireplace fuelled with solids, such as wood, has an exhaust-gas inlet opening (6) and an exhaust-gas outlet opening (7, 7'). According to the invention, at least one of the electrodes is designed to be catalytic, i.e. is made of catalytic material or has a catalytic coating, for example. Alternatively or in addition, according to the invention the exhaust-gas cleaning device is equipped with at least one filter and one bypass. An exhaust-gas catalytic converter is preferably used as filter.

Description

[0001] Exhaust gas purification system

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to an exhaust gas purification device suitable for purifying exhaust gases from solid fuel combustion systems, such as wood-fired fireplaces, according to the preamble of claim 1 and claim 13. The invention also relates to a solid fuel combustion system, e.g., a wood-fired combustion system, with an exhaust gas purification device according to claim 20.

[0004] BACKGROUND OF THE INVENTION

[0005] Experience has shown that fireplaces fueled by wood or other solid fuels emit exhaust gases laden with carbon monoxide (CO), soot, and other pollutants, which contribute to environmental pollution. The pollutant load in the exhaust gases of small combustion systems, especially those commonly used in residential areas, is relatively high. To reduce these emissions, electrostatic particle precipitators (ESP) have been used to reduce particulate matter and / or oxidation catalysts to reduce harmful gases such as CO or other hydrocarbon compounds.

[0006] Exhaust gas cleaning processes that use electrostatic particle separators are very efficient methods for reducing particles from exhaust gases. Patent specification EP 2501 480 B1, for example, describes an electrostatic fine dust filter system that is particularly suitable for cleaning exhaust gases from combustion systems. Such an electrostatic fine dust filter system essentially works as follows: Fine dust particles flow with the exhaust air through the exhaust duct. Electrons are released by corona discharge through a high-voltage electrode that is arranged in the exhaust duct and thus in the exhaust air flow. The electrons move due to electrostatic forces from the high-voltage electrode to the counter electrode, which can be designed, for example, as an exhaust duct wall. The fine dust particles contained in the exhaust air flow are charged and also moved to the counter electrode. The fine dust therefore collects on the counter electrode orThe dust accumulates on the flue duct wall and forms coarse dust through agglomeration. These deposits are usually removed automatically by mechanical cleaning or manually by the chimney sweep or operator.

[0007] If the particles are soot- or tar-like due to incomplete combustion, which can be the case with manually fed wood-burning stoves, electrostatic particle separators can cause problems after extended periods of operation, such as flocculation into the surrounding area or chimney fires. Flocculation occurs because soot-containing deposits adhere very poorly to surfaces and are therefore picked up as soot flakes by the exhaust stream, carried along, and expelled via the chimney, thus polluting the surrounding area. Chimney fires are, among other things, the result of tar deposits in the chimney.

[0008] It is known that soot and tar particles can be burned or oxidized on a catalytic surface with sufficient oxygen and sufficiently high temperatures. This phenomenon is exploited, for example, in exhaust gas catalysts or soot particle filters. Exhaust gas catalysts or soot particle filters can be used in motor vehicles, especially diesel vehicles, as well as in wood-fired combustion.

[0009] The fact that organic deposits, especially grease, can be removed using a catalytic surface is utilized in catalytic oven cleaning. For this purpose, the oven is briefly heated to the required temperature, which completely burns off food residues, such as grease splashes.

[0010] However, in catalyst structures, soot and tar-like particles can lead to undesirable deposits under unfavorable temperature conditions and thus to the clogging of the catalyst channels.

[0011] Flue gas systems with a combination of electrostatic particle separator (ESP) and catalyst are known, especially for wood combustion, e.g. available from DROOFF or skantherm® with the electrostatic particle separator

[0012] OekoTube®, as described in patent application EP 2501 480 A1. The catalyst is usually located first in the exhaust flow, where it can benefit from the high temperature of the exhaust gases. This is intended to reduce CO, hydrocarbons, and sometimes soot (through catalytic oxidation). If a catalyst is used, there is always the possibility of clogging.

[0013] Further examples of such systems with upstream catalyst are described, for example, in Development of electrostatic and catalytic emission reduction measures on selected small biomass combustion plants (4th expert discussion on particle separators in domestic combustion plants, March 7, 2013, Straubing, DBFZ, Mirjam Matthes).

[0014] For example, US patent 3,558,286 shows an apparatus for diesel vehicles for removing unwanted gaseous components and entrained particles from vehicle exhaust gases. This apparatus includes a combination of an electrodynamic separator and a catalyst. In this solution, the exhaust gas first flows through the electrodynamic separator to remove particles from the exhaust gas, and then through the catalyst to convert unwanted gaseous components, thus further removing harmful gases from the previously particulate-free exhaust gas.

[0015] The published patent application FR 2944091 A1 discloses a device for purifying combustion gases and vapors from wood-burning heaters. The device comprises a high-voltage electrode for electrifying the vapor particles and a filter structure positioned downstream of the electrode in the flow direction. This filter structure is brought to a different electrical potential to attract and capture the particles present in the exhaust gases through electrostatic action. The filter structure comprises heatable structures and catalytic agents.

[0016] The published patent application DE 10 2006021 133 A1 describes a method and a device for cleaning exhaust gas streams contaminated with pollutants from small combustion plants. According to the method, the exhaust gas stream is catalytically cleaned in a reactor containing a bed of metal chips. The doped metal chips are heated to a starting temperature before first use. It is provided that before, during, or after the catalytic cleaning, the magnetizable particles of the exhaust gas stream are dedusted in a magnetic field in which the reactor is arranged in a cartridge filling the entire clear cross-section of the exhaust pipe and a further element is provided for dedusting the exhaust gas stream. In one embodiment, the catalyst cartridge also serves as a separation electrode. A spray electrode is placed upstream of the catalyst cartridge in the exhaust gas stream.

[0017] The filters described in the aforementioned documents FR 2944 091 A1, DE 102006021 133 have the disadvantage that, due to the dense filter packing, they hinder the exhaust gas discharge to a relatively great extent or cause a significant pressure drop and therefore the risk of clogging is high.

[0018] US Patent No. 5,424,044 discloses an integrated system for selective catalytic reduction and electrostatic precipitator (i.e., an SCR / ESP system). Catalytic collector plates are used to remove NOx and particulates. Ammonia, injected either directly into the electrostatic precipitator (ESP) or upstream, catalytically reduces NOx to nitrogen and water. The excess ammonia helps capture particulates in the electrostatic precipitator (ESP), thus avoiding the problem of ammonia leakage. The SCR catalyst precipitator plates are positioned in at least one field of the ESP, and preferably at least in the first field of the ESP.

[0019] US Patent No. 5,300,270 discloses a hot-side electrostatic precipitator that removes particulate matter from a NOx-containing flue gas stream. The exiting flue gas stream has a temperature of at least 450°F. The electrostatic precipitator contains a plurality of separation surfaces arranged in a series of arrays. At least some of the separation surfaces are equipped with a catalyst that promotes a reaction between NOx in the flowing flue gas and an added nitrogen-containing compound. Preferably, a nitrogen-containing compound such as ammonia is electrically charged and injected into the flue gas stream before it flows over the catalyst-coated collection surfaces.

[0020] The published patent application US 2023 / 0249195 A1 shows an air purification device for use in aircraft or cars or as stationary units.The air purification device comprises an electrical filter module through which air to be cleaned can flow, and a first electrode and a second electrode between which the air to be cleaned flows and between which a first electrical field can be generated by applying a high electrical voltage provided by a power supply module, wherein the first electrode and the second electrode form an ionizer and wherein a mechanical filter module with a mechanical filter element is arranged behind the electrical filter module in the flow direction of the air to be cleaned, wherein a third electrode is provided in the mechanical filter element or in the mechanical filter module behind the mechanical filter element and wherein a second electrical field can be generated between the second electrode and the third electrode by applying an electrical voltage.

[0021] The known state of the art does not provide any or no satisfactory solution to avoid the problem of flocculation and tar formation in wood-fired combustion plants or other solid fuel combustion plants equipped with electrostatic particle separators (ESP).

[0022] TASK

[0023] It is therefore an object of the present invention to provide an exhaust gas purification device and an exhaust gas purification method in which the problem of flocculation and tar formation does not occur or is less than in known exhaust gas purification systems with electrostatic particle separators. In particular, it is an object of the present invention to provide an exhaust gas purification device and an exhaust gas purification method which, in relation to exhaust gas purification with conventional electrostatic particle separators, have improved exhaust gas values, in particular with regard to flocculation and / or tar formation. In particular, the entrainment of soot in the exhaust gas stream and the problems resulting therefrom are to be reduced, and the risk of chimney fires is to be reduced. In particular, it is an object to provide such an exhaust gas purification device or such an exhaust gas purification method for solid fuel combustion plants, such asWood-burning systems, in particular small solid fuel or wood-burning systems, e.g., those with a maximum output of 50 kW (including, for example, single-room fireplaces, stoves, tiled stoves, baseboard ovens, chimneys, i.e., domestic fireplaces, in particular according to EN 16510-2-x). Therefore, a further object of the present invention is to provide an exhaust gas purification device and an exhaust gas purification method for solid fuel combustion systems, in particular wood-burning systems, used in the private or domestic sector.

[0024] DESCRIPTION OF THE INVENTION

[0025] The invention relates to an exhaust gas purification device according to claim 1, which is particularly suitable for purifying exhaust gases from solid fuel combustion systems, such as from wood-fired fireplaces. The exhaust gas purification device is designed as an electrostatic particle separator for arrangement in an exhaust gas stream, in particular in an exhaust gas stream of a wood-fired fireplace, wherein the exhaust gas purification device has a separation chamber, wherein at least one first electrode, which is preferably designed as a spray electrode, and at least one second electrode, which is designed as a counter electrode, are arranged in the separation chamber, and wherein the separation chamber has an exhaust gas inlet opening and an exhaust gas outlet opening, preferably on opposite sides of the separation chamber, for the purpose of passing an exhaust gas stream, in particular an exhaust gas stream of a wood-fired fireplace.According to the invention, at least one of the electrodes is catalytic, ie, for example, is made of catalytic material or is catalytically coated.

[0026] The exhaust gas purification system described has the particular advantage that soot and, if present, tar, which accumulate on the electrodes and other surfaces due to electrostatic particle deposition, are burned or oxidized on these surfaces if these are catalytically designed. This has the further advantage that, over time, less soot and, if present, tar remains on the catalytic electrode surfaces, thus, in particular, also solving the problem of

[0027] The accumulation of soot and its subsequent flocculation into the surrounding area is reduced. The flocculation escaping from the exhaust gas purification device according to the invention into the environment is therefore lower than in a system whose electrodes, especially their counter electrode, are not catalytically designed. This also has the additional advantage that any downstream catalysts are significantly less likely to become clogged by soot.

[0028] The advantageous design variants listed below lead, either individually or in combination with one another, to further improvements in the exhaust gas purification system.

[0029] In a preferred embodiment, the exhaust gas purification device is characterized in that the counter electrode is catalytic.

[0030] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode is catalytic.

[0031] In a particularly preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode and the counter electrode are catalytically designed.

[0032] In a preferred embodiment, the exhaust gas purification device is characterized in that at least surface portions of the counter electrode which face the spray electrode are catalytically designed.

[0033] In a preferred embodiment, the exhaust gas purification device is characterized in that the separation chamber has an enlarged passage cross-section compared to the exhaust gas inlet opening.

[0034] In a preferred embodiment, the exhaust gas purification device is characterized in that the at least one first electrode is surrounded by the at least one second electrode, e.g., by the at least one second electrode being designed as a lining or wall of the separation chamber. Preferably, the minimum width of the separation chamber (or diameter of the separation chamber transverse to the flow direction) is at least 50 mm, more preferably at least 60 mm, more preferably at least 80 mm, and particularly preferably at least 100 mm.

[0035] Advantageously, the at least one first electrode and the at least one second electrode, i.e. in particular the spray electrode and counter electrode, are arranged at least partially on the same level with one another or next to one another in the flow direction of the exhaust gas flow, wherein or preferably the at least one second electrode can have a longer dimension in the flow direction than the at least one first electrode, so that preferably the at least one second electrode can protrude upstream and / or downstream beyond the at least one first electrode.

[0036] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode and the counter electrode are connected or can be connected to a field ionization source, in particular to a voltage source, for the purpose of generating an electric field.

[0037] In a preferred embodiment, the exhaust gas purification device is characterized in that the counter electrode serves as a separation electrode, in particular that the counter electrode is grounded. The spray electrode is advantageously negatively polarized relative to the counter electrode.

[0038] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode is a high-voltage electrode, preferably with a voltage source in the range of 3 kV - 100 kV.

[0039] In a preferred embodiment, the exhaust gas purification device is characterized in that it is equipped with a heater for heating the catalytically designed electrodes, e.g. for heating to a temperature in the range of 100°C to 500°C, which is sufficiently high that particles deposited on the catalytically designed electrodes during operation, in particular soot or tar particles, burn off.

[0040] In a preferred embodiment, the exhaust gas purification device is characterized in that the catalytically designed electrode or electrodes contain materials, in particular have surfaces made of materials selected from the group consisting of precious metals, in particular gold, platinum and palladium, other metals, ceramic materials, in particular oxides, e.g. cerium dioxide (CeO2), vanadium pentoxide (V2O5), iron(III) oxide (Fe2O3), lanthanum oxide (La2O3), titanium dioxide (TiO2) and zirconium dioxide (ZrO2), salts, in particular potassium salts (K2CO3) and combinations thereof.

[0041] In a preferred embodiment, the exhaust gas purification device is characterized in that the catalytically designed electrode(s), in particular their surfaces, are made of foam materials, e.g., ceramic foam, metal foam, or polymeric foams, which themselves have a catalytic effect or have a catalytically active coating. Preferred foam materials are foam ceramics, e.g., consisting essentially of the group comprising silicon carbide, aluminum oxide, cordierite, zirconium oxide, or combinations thereof, or metallic foam, e.g., consisting essentially of stainless steel or FeCrAl.

[0042] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode is made essentially of a foam material that may optionally be catalytically coated, in particular, for example, a foam material made of a foam ceramic, for example, consisting essentially of a material from the group comprising silicon carbide, aluminum oxide, cordierite, zirconium oxide, or combinations thereof, or of a metallic foam, for example, consisting of stainless steel or FeCrAl. Electrically conductive foam ceramics are particularly preferred.

[0043] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode is disk-shaped or plate-shaped, with a foam ceramic disk being particularly preferred as the spray electrode.

[0044] In a preferred embodiment, the exhaust gas purification device is characterized in that the disc-shaped or plate-shaped spray electrode is arranged substantially in the exhaust gas flow and substantially transversely to the exhaust gas flow.

[0045] If the at least one spray electrode is designed as a plate electrode, it is preferably arranged such that the surface normal of the plate electrode is aligned substantially parallel to the exhaust gas flow (or parallel to the extension of the separation chamber in the flow direction). This can generate turbulence in the exhaust gas flow flowing toward the plate. If the at least one spray electrode is designed as a rod electrode, it is preferably arranged such that the rod electrode and exhaust gas flow (or the rod electrode and the extension of the separation chamber in the flow direction) are aligned substantially parallel.

[0046] In a preferred embodiment, the exhaust gas purification device is characterized in that a filter is arranged upstream and / or downstream of the separation chamber in the exhaust gas flow and optionally a bypass is guided around the filter or around the filter and the separation chamber.

[0047] In an advantageous embodiment, the exhaust gas cleaning system is characterized by the fact that it includes a filter downstream of the separation chamber. A downstream filter has the positive effect of retaining coarse dust. This means that there is little to no flocculation in the area surrounding the solid fuel combustion system or the wood combustion system. A disadvantage, however, is that the filter can become clogged at low temperatures due to this coarse dust. With a downstream filter, active cleaning of the electrodes (e.g., mechanically or thermally) is relatively easy to carry out, since the material removed by the electrodes falls downwards (ideally back into the combustion chamber) without contaminating the filter, since the filter is located above the electrodes in a downstream arrangement.

[0048] In a preferred embodiment, the exhaust gas purification device is characterized in that the filter(s) are gas-permeable catalysts, ie exhaust gas catalysts.

[0049] In an advantageous embodiment, the exhaust gas purification system is characterized in that it includes a filter upstream of the separation chamber. An upstream filter is closer to the combustion chamber and therefore tends to have a higher temperature than a downstream arrangement. This can be particularly advantageous if the filter is designed as a gas-permeable catalyst, since the catalyst reaches operating temperature more quickly due to the upstream arrangement. To achieve better function of the catalytic conversion of gases, especially CO, a heating element can be provided to heat the filter, especially if it is designed as a gas-permeable catalyst. Such a heater could, for example, be used periodically to clean the filter element.

[0050] Although a filter has advantages, versions without a filter are preferred because then the problem of blockage and the associated failure of the exhaust gas cleaning system does not exist. Also, no bypass is then necessary, which means that the construction of an exhaust gas cleaning system can be kept simple and cost-effective.

[0051] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode is designed as an elongated, in particular rod-like electrode.

[0052] In a preferred embodiment, the exhaust gas purification device is characterized in that the counter electrode is designed as a wall or wall element, particularly for lining an exhaust duct. The counter electrode thus forms a channel for the exhaust gas flow. Due to this described design and the mutual arrangement of the electrodes, the counter electrode can offer a large separation surface.

[0053] In a preferred embodiment, the exhaust gas purification device is characterized in that the counter electrode surrounds the spray electrode, in particular in that the counter electrode is designed in a cylindrical shape, e.g. as a cylindrical wall, and preferably projects beyond the length of the spray electrode.

[0054] In a preferred embodiment, the counterelectrode extends beyond the extension of the spray electrode, toward the exhaust gas inlet opening on the one hand and the exhaust gas outlet opening on the other, and can optionally extend to these exhaust gas inlet and exhaust gas outlet openings. In this case, the counterelectrode is expediently also designed to be catalytic over its entire surface in the aforementioned extension, i.e., for example, made of catalytic material and / or catalytically coated. This embodiment is particularly preferred if the spray electrode is designed as a rod electrode and is arranged in the separation chamber such that its longitudinal extension is aligned according to the general flow direction in the separation chamber.This design is also advantageous if the spray electrode is designed as a plate electrode and is arranged in the separation chamber in such a way that its surface normal is aligned according to the general flow direction in the separation chamber.

[0055] If the counter electrode extends beyond the extension of the spray electrode in the direction of flow and in the counter flow direction and the counter electrode is catalytic to the same extent beyond the extension of the spray electrode, a particularly good separation efficiency can be achieved.

[0056] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode has edges, wherein the sum of the lengths of the edges preferably corresponds at least to the longitudinal dimension of the spray electrode or exceeds it, preferably at least twice and more preferably four times.

[0057] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode has a plurality of tips.

[0058] In a preferred embodiment, the exhaust gas purification device is characterized in that the spray electrode protrudes between opposing sections of the counter electrode, in particular, for example, is arranged substantially axially centrally in a cylindrical counter electrode.

[0059] In a preferred embodiment, the exhaust gas purification device is characterized in that a cleaning device and / or a retention container or chamber for dedusting at least the counter electrode are provided in the separation chamber. The cleaning device can be designed, for example, as a cage, e.g., made of metal. A retention container is particularly useful in exhaust gas purification device designs that have an expanded passage cross-section compared to an exhaust duct that feeds into an exhaust gas purification device from below. The invention further relates to an exhaust gas purification device according to claim 13, which is particularly suitable for cleaning exhaust gases from solid fuel combustion systems, such as from wood-fired fireplaces.This exhaust gas purification device is also designed as an electrostatic particle separator for arrangement in an exhaust gas stream, in particular in an exhaust gas stream of a wood-fired fireplace, wherein the exhaust gas purification device has a separation chamber, wherein at least one first electrode, which is preferably designed as a spray electrode, and at least one second electrode, which is designed as a counter electrode, are arranged in the separation chamber, and wherein the separation chamber has an exhaust gas inlet opening and an exhaust gas outlet opening on preferably opposite sides of the separation chamber for the purpose of passing through an exhaust gas stream, in particular an exhaust gas stream of a wood-fired fireplace.According to the invention, it is provided that the exhaust gas purification device is equipped with at least one filter and one bypass, in particular a bypass around at least the at least one filter. The filter and bypass can also be implemented in a corresponding manner in the previous exhaust gas purification device.

[0060] This exhaust gas purification device has the particular advantage that even if the filter becomes clogged, the exhaust gas can be allowed to flow away via a bypass.

[0061] The advantageous design variants listed below, alone or in combination with one another, lead to further improvements in the exhaust gas purification system.

[0062] In a preferred embodiment, the exhaust gas purification device is characterized in that the bypass originates from a bottleneck of the exhaust gas flow in an exhaust duct section leading to the exhaust inlet opening or in an exhaust duct section leading away from the exhaust gas outlet opening. Preferably, the bottleneck originates from a point of the smallest cross-section of the bottleneck of the exhaust gas flow in order to lead back into the exhaust gas flow after circulating through the at least one filter.

[0063] In a preferred embodiment, the exhaust gas purification device is characterized in that the bottleneck is essentially formed by two mutually directed, converging, in particular trapezoidal or conical structures, which, where they join, form a point or passage of the smallest cross-section of the bottleneck, wherein the point of the smallest cross-section of the bottleneck is preferably designed as a cylindrically shaped passage between the cones. The cylindrically shaped passage between the cones preferably extends over a shorter distance along the exhaust gas flow than the two cones combined. More preferably, the cylindrically shaped passage between the cones extends over a shorter distance along the exhaust gas flow than each of the two cones individually.

[0064] In a particularly expedient embodiment, the bottleneck is arranged eccentrically relative to the filter, e.g., so that the two mutually directed, converging, particularly trapezoidal or conical structures are obliquely formed. At the point or passage of the smallest cross-section, the bottleneck has two opposing side regions, the first side region on the maximally eccentric side, and the second side region on the minimally eccentric side of the smallest cross-section relative to the filter. The bypass essentially leads away from the minimally eccentric side region, or the minimally eccentric side region has a bypass discharge opening.

[0065] The exhaust duct section positioned upstream of the bottleneck in the exhaust gas flow direction is preferably designed such that the bottleneck is approached at an angle, in particular so that the exhaust gas flow in the bottleneck is deflected past a bypass discharge opening. Due to the deflection and constriction, the flow velocity of the exhaust gas over the bypass discharge opening, especially that near the opening, is accelerated particularly strongly.

[0066] In a preferred embodiment, the exhaust gas purification device is characterized in that the bottleneck is designed such that the exhaust gas flow widens after the bottleneck and before the filter, in particular to a cross-sectional area value which substantially corresponds approximately to that of the exhaust gas duct before the bottleneck.

[0067] In a preferred embodiment, the exhaust gas purification device is characterized in that the ratio of the cross section of the exhaust gas flow at the narrowest point of the bottleneck to the cross section of the exhaust gas flow downstream of the exhaust gas flow upon entry into the filter is in the range of 1:1.5 to 1:5, preferably in the range of 1:2 to 1:3.

[0068] In a preferred embodiment, the exhaust gas purification device is characterized in that the ratio of the cross-section of the exhaust gas flow at the narrowest point of the bottleneck to the cross-section of the exhaust gas flow upstream of the bottleneck (or at the base of the bottleneck) is in the range from 1:1.5 to 1:5, preferably in the range from 1:2 to 1:3.

[0069] In a preferred embodiment, the exhaust gas purification device is characterized in that the filter is arranged upstream and / or downstream of the separation chamber in the exhaust gas flow and the bypass is guided around the filter or around the filter and the separation chamber

[0070] In a preferred embodiment, the exhaust gas purification device is characterized in that, in the case of an upstream filter, the bypass is guided around the filter but not around the separation chamber or, preferably, the bypass is guided around the filter and around the separation chamber.

[0071] In a preferred embodiment, the exhaust gas purification device is characterized in that, in the case of a downstream filter, the bypass is guided around the separation chamber and around the filter or, preferably, the bypass is guided around the filter but not around the separation chamber.

[0072] In a preferred embodiment, the exhaust gas purification device is characterized in that the filter is a gas-permeable catalyst.

[0073] In a preferred embodiment, the exhaust gas purification device is characterized in that the filter is designed in such a way, in particular can be inserted or is inserted into an exhaust gas duct in such a way that it essentially spans the cross section of an exhaust gas duct or an exhaust gas flow, so that the entire exhaust gas flow flows through the filter, insofar as it does not flow through the bypass.

[0074] The invention further relates to a solid fuel combustion plant or wood combustion plant according to claim 20. The wood combustion plant comprises a furnace housing with a fireplace and an exhaust gas purification device in one of the previously described embodiments.

[0075] In a preferred embodiment, the solid fuel combustion system or wood combustion system is characterized in that the exhaust gas purification device is integrated into the furnace housing or mounted on the furnace housing. In an alternative embodiment, the solid fuel combustion system or wood combustion system is characterized in that the separation chamber has a larger cross-section than an exhaust duct for the exhaust gas flow, which is fed from the combustion system to the exhaust gas purification device via the exhaust gas inlet opening.

[0076] In a preferred embodiment, the solid fuel combustion system or wood combustion system is characterized in that the furnace housing and exhaust gas purification device are coordinated and designed in such a way that, during operation of the system, the temperature of at least one of the catalytically designed electrodes, preferably at least one catalytically designed counter electrode, is or can be regulated to an operating temperature at which particles, in particular tar or tar particles, which are deposited on the at least one catalytically designed electrode during operation of the system can be decelerated. For this purpose, the furnace housing and exhaust gas purification device are preferably coordinated and designed in such a way that the at least one of the catalytically designed electrodes can be maintained at the aforementioned operating temperature due to the thermal energy of the exhaust gas flow that flows from the combustion chamber during operation.

[0077] The required minimum operating temperature depends on the catalyst used and the activation temperature of the soot or tar oxidation of the catalyst. Catalysts with an activation temperature in the range of 100°C to 500°C are advantageous. The required temperature is ensured, for example, by selecting the distance of the exhaust gas purification device in the exhaust stream from the combustion chamber such that the temperature in the electrostatic particle separator, and thus the temperature of the catalytically designed electrodes due to the hot exhaust gases flowing through them, is at or above the activation temperature, so that particles deposited on the catalytically designed electrodes or surfaces, in particular soot or tar particles, can burn off.

[0078] Furthermore, the exhaust gas cleaning system or the solid fuel combustion system or wood combustion system can be equipped with a heater, particularly for the initial heating of the catalytically designed electrodes, so that the operating temperature of the electrodes can be reached as quickly as possible. A control device for regulating the heater can be provided. Instead of the individual electrodes or in addition to them, the separation chamber or the exhaust gas cleaning system as a whole can be equipped with a heater. Other components can also be equipped with a heater. These include, for example, the filter(s). The respective heater is particularly designed for short-term use during ignition or shortly before ignition for the rapid adjustment of an operating temperature of the respective component that is higher than room temperature, so that particles or harmful gases can be filtered out or removed as quickly as possible from the start of combustion.can be reduced and / or condensate formation can be minimized.

[0079] The optional features mentioned can be implemented in any combination, provided they are not mutually exclusive. In particular, where preferred ranges are specified, further preferred ranges result from combinations of the minimums and maximums specified in the ranges.

[0080] Further advantages, features and preferred embodiments of the invention will become apparent from the following detailed description of the invention with reference to figures.

[0081] BRIEF DESCRIPTION OF THE CHARACTERS

[0082] They show in a not to scale, schematic representation: Figure 1: Variants of an electrostatic precipitator according to the invention, each in longitudinal section, (a) with rod electrode, (b) with plate electrode, (c) with lateral channel outlet;

[0083] Figure 2: Design variants of the separation electrode of an electrostatic precipitator, each in cross section, in the form of (a) a square tube section, (b) a square tube section with internal partition walls, (c) a circular cylinder, (d) a circular cylinder with an internal serrated structure (e) a square tube section in combination with an alternative spray electrode;

[0084] Figure 3: Variants of an electrostatic precipitator according to the invention with filter and bypass, each in longitudinal section, (a) with downstream filter and bypass around the filter, (b) with upstream filter and bypass around the filter, (c) with downstream filter and bypass around the separation chamber and filter, (d) with upstream and downstream filter and bypass around both filters and the separation chamber;

[0085] Figure 4: Equipment variants with filter and bypass in longitudinal section, (a) of an exhaust pipe section and (b) of an exhaust pipe section with extension section, each essentially with a concentrically arranged constriction, (c) of an exhaust pipe section with extension section with an essentially eccentrically arranged constriction;

[0086] Figure 5: Variants of an electrostatic precipitator with filter and bypass, each in longitudinal section, (a) with downstream filter and bypass around separation chamber and filter, (b) with upstream filter and bypass around the filter, (c) with upstream filter and bypass around filter and separation chamber, (d); with upstream and downstream filter and with bypass around both filters and the separation chamber; Figure 6: Wood-fired stove with exhaust gas cleaning device, where (a) the exhaust gas cleaning device is integrated into the stove housing or directly connected to it, (b) the exhaust gas cleaning device is connected downstream of the stove housing at a distance, (c) the exhaust gas cleaning device is connected downstream of a preheater and at a distance from the open housing, (d) the exhaust gas cleaning device is heated;

[0087] Figure 7: Exhaust duct section with heated filter;

[0088] Figure 8: Separation chamber of an electrostatic precipitator designed with heated catalytic walls;

[0089] Figure 9: Separation chamber of an electrostatic precipitator designed (a) with cleaning device and dust collector and (b) additionally with service hatch.

[0090] DETAILED DESCRIPTION OF THE FIGURES

[0091] The invention is described in more detail below with reference to the figures. In some cases, the same reference numerals are used for identical or functionally identical elements (in different figures). An apostrophe can be used to distinguish identical or functionally identical or functionally similar elements in a further embodiment.

[0092] In Fig. 1 (a) and (b), variants of an electrostatic precipitator 1, 1' according to the invention are each shown in longitudinal section. The electrostatic precipitator 1 has a separation chamber 15 with at least two electrodes 11, 13. An electrostatic precipitator is or will be integrated into or connected to an exhaust gas duct 8 and 9 in such a way that the exhaust gas flow from a fireplace flows through the electrostatic precipitator. The exhaust gas flow flows essentially from an inlet opening 6 to an outlet opening 7, preferably in such a way that the general flow direction (also flow direction) of the inflowing exhaust gas flow at the inlet essentially corresponds to the general flow direction of the outflowing exhaust gas flow at the outlet. The outgoing exhaust gas duct 9 is, as it were, a straight continuation of the incoming exhaust gas duct 8 upon entering the separation chamber 15 when exiting the separation chamber.According to an alternative variant, as shown in Fig. 1 (c), the outgoing duct 9' can optionally be arranged at an angle to the incoming duct 8 (for example at an angle of approximately 90 degrees, i.e. transverse to the incoming flow direction). The separation chamber 15 can have an internal cross-section (internal diameter) transverse to the general flow direction that is larger than the internal cross-section (internal diameter) of the connected supply and / or discharge parts of the exhaust duct, 8 or 9 or 9', as shown in Figs. 1 (a), (b) and (c). Alternatively, a section of an exhaust duct could be defined and designed as a separation chamber, which essentially corresponds to the cross-section or the cross-sectional dimensions (e.g. the diameter) of the exhaust duct.

[0093] The electrostatic precipitator includes at least a first electrode 11 and a second electrode 13. The first electrode 11 is also referred to below as the spray electrode. The second electrode 13 is also referred to below as the counter electrode or separation electrode. The two electrodes are arranged in the separation chamber 15, 15'. The first and second electrodes are in particular arranged at a distance from one another. The spray electrode 11 is preferably arranged essentially centrally in the separation chamber 15. Expediently, the spray electrode 11 is arranged, for example, essentially in a region of the separation chamber that lies on a direct flow path between the inlet opening 6 and the outlet opening 7. In Fig. 1 (a) or Fig. 1 (b), for example, the direct flow path lies in the region of the straight connecting path between the inlet opening 6 and the outlet opening 7.The separation chamber 15 is preferably at least partially lined by the counter electrode 13 or is essentially defined by the counter electrode 13. The spray electrode 11 is expediently essentially surrounded by the counter electrode 13, in particular encircled, encompassed and / or enclosed. The counter electrode 13 expediently has a surface area that is many times larger than the spray electrode 11, e.g. a surface area that is more than 10 times, more than 20 times or more than 100 times larger. An insulator 17 insulates the two electrodes 11 and 13 from one another. By means of a voltage source (not shown here), a voltage difference can be generated between the spray electrode 11 and the counter electrode 13, whereby an electric field is created between the spray electrode 11 and the counter electrode 13.The voltage source is expediently a high-voltage generation system, by means of which a voltage difference of at least 3 kV, particularly preferably in the range from 3 kV to 100 kV, or optionally more than 100 kV, can be applied. The voltage source is preferably installed outside the separation chamber 15. During operation, the first electrode or the spray electrode 11 is expediently usually negatively polarized relative to the counter electrode 13 and is thus electrode-emitting. The counter electrode 13 is expediently grounded. Grounding the counter electrode also serves for safety and the protection of persons from uncontrolled discharge and electric shock.If a voltage is applied between the two electrodes 11 and 13, according to theory, dust particles are electrically charged by the corona discharge of the spray electrode 11 and are drawn in the electric field to the oppositely charged electrode 13 and deposited on its surface. In practice, deposits will also be found on the surface of the spray electrode. For use in the exhaust gas flow of an exhaust duct of a solid fuel combustion system or wood combustion system, the spray electrode is advantageously designed as a rod electrode 11 or rod-shaped electrode (Fig. 1 (a)). Alternatively, other shapes can also be used, such as a plate electrode 11' (Fig. 1 (b)). Rod-shaped electrodes made of at least one cambered piece of spring sheet metal, in particular spring steel sheet that is cambered transversely to the longitudinal direction of the electrode, as disclosed in the published patent application WO 2011 / 060562 A1, are particularly suitable.The spray electrode may have sharp edges and / or protruding tips because the density of the field lines and thus the electric field strength at edges and tips is particularly high compared to other parts of the electrode, thus favoring corona discharge.

[0094] The spray electrode 11 and the counter electrode (or the deposition electrode) 13 are arranged relative to one another in such a way that, when voltage is applied, an electric field builds up between them, i.e., field lines extend from one electrode to the other. The counter electrode 13 preferably surrounds the spray electrode 11, 11', in particular, for example, by the counter electrode 13 being designed in a cylindrical shape, e.g., as a cylindrical wall or wall lining, which surrounds, in particular encircles, encompasses and / or encloses the spray electrode 11, 11', and preferably projects beyond the spray electrode 11, 11' (or beyond the dimension of the spray electrode) in its cylindrical axial extent (Fig. 1(a) and Fig. 1(b)) or, in the case of the rod-shaped spray electrode 11, in particular projects beyond the length of the spray electrode 11 (Fig. 1(a)).

[0095] In one embodiment, a section of an exhaust gas duct can be designed as a counter electrode or lined with one and equipped with a spray electrode approximately in the center of the duct, so that this section serves as a separator. In another embodiment, as shown in Fig. 1(a) and Fig. 1(b), a housing with a passage cross-section that is wider than the adjacent sections of the exhaust gas duct 8, 9 can be installed between sections of an exhaust gas duct, which housing is equipped with a counter electrode and electrode as a separation chamber 15. In such an embodiment, the separation chamber 15 can also have wall regions 14 in the transition region to the exhaust gas duct that are oriented transversely and / or obliquely to the exhaust gas flow direction. These wall regions 14 can also be equipped as a counter electrode or part of the counter electrode.

[0096] An exhaust pipe of a small combustion plant (or the cross-section of the exhaust gas flow through which the exhaust gas flows) typically has a diameter in the range of, for example, 100 mm to 300 mm. An exhaust gas purification device expediently has a separation chamber, i.e., a flow-through diameter that is either equal to or larger than the diameter of the exhaust pipe. For small combustion plants, separation devices are particularly expedient which have a separation chamber with a diameter in the range of 100 mm to 1500 mm, or preferably 120 mm to 500 mm, wherein the diameter of the separation chamber is preferably equal to or larger than the diameter of the incoming exhaust pipe, if one is present.

[0097] If a separation chamber 15 has a larger cross-section than the exhaust duct 8 through which the exhaust gases coming from a combustion plant are fed to the separation chamber 15 of the exhaust gas purification system, the velocity of the exhaust gas flow in the separation chamber 15 is slower than in the incoming exhaust duct 8. Slowing the flow velocity leads to a longer residence time in the separation chamber and thus to a higher separation efficiency. Mineral dusts that cannot be converted catalytically also increasingly settle in the separation chamber and can be collected and removed there.

[0098] Preferably, the ratio of the cross-section of the separation chamber 15 to the cross-section of the supply exhaust duct 8 or the exhaust inlet opening 6 of the separator is 1.1:1 or more. A ratio in the range of 1.2:1 to 20:1 is preferred, and a ratio in the range of 1.2:1 to 10:1 is more preferred.

[0099] According to the invention, the counter electrode 13 and / or the discharge electrode 11, 11' can be catalytically designed, i.e., made of catalytic material or coated with catalytic material. Catalytic surfaces have the advantage of being self-cleaning, in that material deposited on them converts into gaseous substances and / or compounds. Above a certain temperature, catalytic surfaces can promote the burning of soot and tar deposited on them, which are produced, for example, during wood combustion. Furthermore, CO can be converted to CO2 on catalytic surfaces above a certain temperature.

[0100] The catalytically designed electrodes can be made of or contain conventional catalyst materials. In particular, at least the surface of the electrodes contains catalytically active material. Furthermore, the catalytically active surface of the electrodes can optionally be porous or uneven, i.e., rough, which can increase the dimensions of the catalytically active surface compared to an unstructured surface.

[0101] Preferably, the electrodes (ie spray and / or counter electrode) or at least their surfaces can be made entirely or partially from an electrically conductive catalytically active material.

[0102] For example, the electrodes (i.e., spray and / or counter electrode) can be made of an electrically conductive carrier material with a catalytic coating. Porous coatings (such as a washcoat) made of catalytically active material are particularly suitable as coatings. Optionally, the carrier material can be porous. One example of this is a catalytically coated metal honeycomb. Suitable coatings include, for example, catalytically active metal or precious metal coatings, but also catalytically active ceramic coatings, particularly metal oxide and mixed metal oxide coatings.

[0103] The spray and / or counter electrode can optionally be shaped in such a way that, due to their shape and mutual arrangement, eddies or turbulence arise in the exhaust gas flow within the electrostatic particle separator. This optimises the flow to the electrode surfaces, thus promoting contact with and thus the degradation of particles and gaseous components of the exhaust gas on the catalytic surfaces. Such optimisation can be achieved, for example, with a plate-shaped spray electrode 11', the surface area of ​​which is positioned essentially transversely to the exhaust gas flow. The flow eddies or turbulence resulting from this arrangement of a plate electrode 11' can promote the conversion of the harmful substances, compounds and particles contained in the exhaust gas at the counter electrode.

[0104] Fig. 2 shows four variants of separation electrodes 23, 23', 23", 23'" of an electrostatic precipitator, each in cross-section. These are in the form of a square tube section (Fig. 2 (a)), a square tube section with internal partition walls 25 (Fig. 4 (b)), a circular cylinder (Fig. 2 (c)), and a circular cylinder with an internal serrated structure (segmented jacket lining 27) (Fig. 2 (d)). One or more spray electrodes 21, also shown in cross-section, are arranged at a distance from the separation electrode in the cavity spanned by the respective separation electrode. The cross-section of the spray electrodes 21 can expediently be cross-shaped, as shown in the illustration. Alternatively, spray electrodes, which are designed as rods or rod-like, can also have needle-like tips distributed over the length of the rod-like electrode.In cavities surrounded by deposition electrode surfaces - especially those that have greatly varying wall distances towards their center - it can be useful to arrange a plurality of spray electrodes or to design the shape of the spray electrode so that the electric field spreads as optimally as possible throughout the entire cavity or that the deposition is distributed as evenly as possible over all deposition surfaces, thus allowing the catalytic properties of the deposition electrode surfaces to be utilized as optimally as possible. An example of this is shown in Fig. 2 (a), where the electrostatic precipitator has a rectangular cross-section. Here, the spray electrode is formed, for example, by two rods 21 arranged parallel to one another. In a variant, a single electrode 21' can be used instead of two rod electrodes 21, e.g., as in Fig.2 (e), with a cross-sectional shape whose side dimensions are selected essentially according to the ratio of the side dimensions of the cross section of the deposition electrode 23. In contrast to the parallel, spaced-apart arrangement of two or more rod electrodes 21, e.g., according to Fig. 2 (a), a single rod-shaped electrode 21' with a cross-sectional shape adapted to the deposition chamber in its cross-section, e.g., according to Fig. 2 (e), has a closed surface through which no flow can pass. Instead of a rod electrode or an arrangement of several rod-shaped spray electrodes aligned parallel to one another, through which the exhaust gas can flow, it may be expedient to use a single plate-shaped spray electrode (see also Fig. 1 (b)) or an arrangement of a plurality of plate-shaped electrodes (not shown in the figures), e.g., arranged parallel to one another in the extension of their normals.Optionally, additional needle-like tips can be provided on the plate edges and / or plate corners of a plate-shaped electrode, which serve as spray tips (similar to the illustration in Fig. 2 (e)). Plate-shaped spray electrodes are advantageously designed as open-pore foam ceramic. The edges on the surface that result from the open pores can optionally serve as spray tips. Furthermore, as shown, for example, in Fig. 2 (b), an electrostatic particle precipitator can be divided into two or more essentially parallel passages or deposition chambers by additional internal partition walls 25. Advantageously, the partition walls 25 are also designed as deposition electrodes, in particular catalytic deposition electrodes 23'. This results in a plurality of cavities framed by counter-electrode surfaces, and thus a relatively large deposition area.If such internal partition walls 25 are present, it is also advantageous to position at least one spray electrode 21 in each of the chambers. Other designs of electrostatic precipitators have a round-cylindrical counterelectrode 23" with a central rod electrode, as shown, for example, in Fig. 2 (c). Compared to the design in Fig. 2 (c), in a variant, as shown in Fig. 2 (d), the active area of ​​the counterelectrode 23'" can be enlarged by a serrated design of the counterelectrode surface.

[0105] In order to ensure a minimum distance between the spray electrode and the counter electrode, in practice a minimum width of the cavity(ies) or separation chamber(s) surrounded by counter electrode surfaces is generally not undercut. This minimum width is preferably at least 50 mm, preferably at least 60 mm, more preferably at least 80 mm, and even more preferably at least 100 mm. This is particularly relevant for separation chambers with counter electrodes that are designed as multiple chambers, such as multiple chambers arranged parallel to one another as shown in Fig. 2 (b), and spray electrodes that are placed in the individual chambers at a distance from the chamber walls. The term width here refers in particular to a dimension (especially a diameter) of the separation chamber transverse to the general flow direction.

[0106] Fig. 3 shows four variants of an electrostatic particle separator

[0107] 1"", 1'"", 1"”") with bypass, each in longitudinal section. The spray electrode is preferably designed as a rod electrode 11. The walls 13, 14 of the separation chamber 15 are expediently designed essentially as a counter electrode.

[0108] Fig. 3 (a) shows a first embodiment variant with a filter 31 downstream of the separation chamber 15 and with a bypass 33 around the filter 31. The bypass 33 leads the filter 31 from the separation chamber 15 directly into the outgoing exhaust gas duct 9. In a modification, the bypass 33 could be led around the filter 31 in such a way that it leads from a first point of the outgoing exhaust gas duct 9 upstream of the filter 31 to a second point of the outgoing exhaust gas duct 9 downstream of the filter 31.

[0109] Fig. 3 (b) shows a second embodiment with a filter 31' upstream of the separation chamber 15 and with a bypass 33' around the filter 31'. The bypass 33' leads the filter 31' from the incoming exhaust duct 8 directly into the separation chamber 15. In a modification, the bypass 33' could be led around the filter 31' such that it leads from a first point of the incoming exhaust duct 8 upstream of the filter 31 to a second point of the incoming exhaust duct 8 downstream of the filter 31. Fig. 3 (c) shows a third embodiment with a filter 31 downstream of the separation chamber 15 and with a bypass 33" around the separation chamber 15 and filter 31. The bypass 33" leads the separation chamber 15 and the filter 31 from the incoming exhaust duct 8 directly into the outgoing exhaust duct 9.

[0110] Fig. 3 (d) shows a fourth embodiment variant with a filter 31, 31' upstream and downstream of the separation chamber 15 and a bypass 33"' around the separation chamber 15 and the two filters 31, 31'. The bypass 33" leads the first filter 31', the separation chamber 15 and the second filter 31 from the incoming exhaust duct 8 directly into the outgoing exhaust duct 9.

[0111] The design variants according to Fig. 3 (b) and Fig. 3 (d) with a filter 31' upstream of the electrostatic particle separator have the advantage that the upstream filter 31' cannot be clogged by particles flocculating or flocculated in the particle separator. In contrast to the bypasses 33" and 33'" of the design variants according to Fig. 3 (c) and Fig. 3 (d), the bypasses 33 and 33' of the design variants according to Fig. 3 (a) and Fig. 3 (b) only extend around the respective filter 31 or 31', but not around the entire separation chamber 15.

[0112] The respective filter 31 or 31' essentially spans the entire cross-section of the exhaust duct, so that during normal operation, the exhaust gas flow essentially flows out through the filter 31 or 31'. The bypass serves only as a safety measure, so that in the event of a blockage of the filter 31 or 31', the exhaust gas flow can flow out unfiltered via the bypass.

[0113] The respective filter 31 or 31' can be a gas-permeable catalyst, in particular a commercially available gas-permeable catalyst, i.e., a filter made of catalytically active material. In this case, the surface in the passage openings or pores is particularly catalytically active.

[0114] The respective filter or catalyst 31, 31' is not normally designed as a separation electrode. Preferably, the filter serves as an exhaust gas catalyst, in particular, for example, for the gas-phase oxidation of CO to CO2. Alternatively, the filter can be designed as a catalyst and additionally as a separation electrode. The position of the electrode attachment and thus of the insulator 17, 17' can vary, depending on what is structurally feasible or, for example, depending on the available space.

[0115] To ensure that as little exhaust gas as possible flows unfiltered through the bypass during normal operation, particularly when the filter is functioning normally, the bypass can be equipped with a safety system. A typical system would be a spring-loaded safety flap that only opens when the pressure of the outflowing exhaust gas increases to a pressure value above the pressure during normal operation. The purpose of a safety system is to ensure that unfiltered exhaust gas only flows through the bypass in relevant quantities when the exhaust gas flow through the filter is disrupted, e.g. because the filter is partially or completely blocked. Known safety systems can have the disadvantage of being prone to failure, e.g. because they can jam, like the aforementioned safety system with a mechanically movable flap, or have other defects. It is therefore desirable to use a bypass system that is as fail-safe as possible.

[0116] Fig. 4 presents an improved bypass system according to the invention that does not require any moving parts, particularly moving parts for temporarily blocking the bypass, and is therefore more reliable. The bypass system according to the invention is described below using exemplary embodiments, Figs. 4 (a), 4 (b), and 4 (c).

[0117] Fig. 4 (a), (b) and (c) each show a functional exhaust pipe section 40, 40', 40" in longitudinal section with porous or gas-permeable filters 41, 41', 41' in a main exhaust gas flow guide 42, 42', 42' and a bypass 43, 43', 43" around the filter. The filter 41, 41', 41" spans the entire cross-section of the exhaust gas flow in the main exhaust gas flow guide 42, 42', 42" at one point in the exhaust gas flow, so that ideally the entire exhaust gas flow can flow out through the pores of the filter 41, 41', 41". The filter 41, 41', 41" is located, for example, on a step 44, 44', 44" of the exhaust gas line section and / or is held by a bracket or anchor (not shown) so that the filter is fixed in its position. The bypass 43, 43', 43" leads via a discharge or extraction opening 45, 45', 45" in front of the filter 41, 41', 41" out of the main exhaust gas flow guide 42, 42', 42", past the filter 41, 41', 41" orif necessary around the filter 41 and via a return opening 46, 46', 46" back into the main exhaust gas flow guide 42, 42', 42", in particular from an area in the main exhaust gas flow guide 42, 42', 42" upstream of the filter 41, 41', 41" to an area in the main exhaust gas flow guide 42, 42', 42" downstream of the filter 41, 41', 41". The bypass 43, 43', 43" thus forms an alternative route for the outflow of the exhaust gas, which leads past the filter 41, 41', 41" or around the filter. If the filter 41, 41' is normally permeable, ie the passage openings or the filter pores are not blocked, the exhaust gas flow should essentially flow through the filter 41, 41', 41", ie without leaving the main exhaust gas flow through the main exhaust gas flow, thus if possible without loss or outflow via the bypass. If the filter 41, 41', 41" is (partially or completely) blocked (e.g.due to contamination), the exhaust gas flow is discharged (partially or completely) upstream of the exhaust gas flow in the area before the filter 41, 41', 41" via the bypass 43, 43', 43" due to a build-up of back pressure in the main exhaust gas flow guide 42, 42', 42".

[0118] Preferably, the main exhaust gas flow guide 42, 42', 42" has a passage of reduced cross-section or a bottleneck 47, 47', 47", also called a constriction or narrowing, upstream of the filter 41, 41', 41", where the discharge opening 45, 45', 45" leads into the bypass 43, 43', 43", upstream of the exhaust gas flow, a passage of reduced cross-section or a bottleneck 47, 47', 47", also called a constriction or narrowing. The discharge opening 45, 45', 45" is expediently arranged at a point of the smallest cross-section of the bottleneck 47, 47', 47" or the constriction or narrowing. Due to the constriction at the bottleneck 47, 47', 47", the flow velocity of the outflowing exhaust gas in the bottleneck is locally increased compared to passages before and after the bottleneck, which have a larger diameter or cross-section. than the bottleneck.

[0119] Fig. 4 (a) and Fig. 4 (b) show a concentrically arranged bottleneck 47, 47'. This bottleneck 47, 47' is arranged essentially concentrically in a substantially straight exhaust duct 48, 49, 48', 49' (in particular in the supply exhaust line 48, 48'). The bottleneck 47, 47' is thus arranged concentrically, in particular also with respect to the filter 41, 41' following it in the direction of flow. In this concentric arrangement, the bottleneck 47, 47' is arranged centrally in front of the filter 41, 41' with respect to a line perpendicular to the filter surface. In Fig. 4 (c), however, an eccentrically arranged bottleneck 47" is shown. This bottleneck 47" is essentially eccentrically arranged with respect to the filter 41" in an exhaust gas duct running towards the filter 41" or in the exhaust gas line 48, 48' leading to the filter. The bottleneck 47" is particularly perpendicular to the filter surface (ieto the filter inlet point 51") is arranged laterally offset relative to the center (not centrally in front of, but rather). In particular, for example, as shown in Fig. 4 (c), the bottleneck 47" is arranged laterally offset relative to the center in the perpendicular direction to the filter surface (ie to the filter inlet point 51") but still in a vertical direction in front of the filter 41". The bottleneck 47" is thus arranged eccentrically in relation to the filter 41" following it in the direction of flow and, if applicable, in relation to the supply exhaust gas line 48" containing the bottleneck.

[0120] Insofar as the eccentric bottleneck 47" is laterally offset in the vertical direction to the filter surface relative to a filter center, it is advantageous that the exhaust gas line 48" leading to the bottleneck 47" is also laterally offset relative to the filter center in the vertical direction to the filter surface, whereby the bottleneck 47" and the leading exhaust gas line 48" are laterally offset towards opposite sides, which results in a significant flow deflection in the exhaust gas flow in the bottleneck 47". Insofar as the bottleneck 47" and the supply exhaust line 48" are arranged eccentrically with respect to the filter 41", the two are spaced apart from a filter axis in opposite directions. The eccentric arrangement has the effect that the flow directed to the filter 41" experiences an even stronger deflection around the bypass discharge opening 45" than is the case with a concentric arrangement.The flow is accelerated by narrowing and additional deflection in the bottleneck 47". This acceleration effect occurs at the bypass discharge opening 45" if it is arranged on the less eccentric side region of the eccentric bottleneck 47". The acceleration effect is reinforced by the exhaust gas duct section 48" located upstream of the bottleneck 47" being designed such that the flow approaches the bottleneck 47" as obliquely as possible (i.e. at the largest possible angle to a normal to the cross-section of the narrowest point in the bottleneck). The discharge opening 45, 45', 45" can be designed as a longitudinal opening, in particular as a slot, which is oriented longitudinally transversely to the direction of the exhaust gas flow, at the point of the smallest cross-section of the bottleneck 47, 47', 47".

[0121] In the case of a bottleneck 47, 47' arranged concentrically in an exhaust line section, e.g. according to Fig. 4 (a) and Fig. 4 (b), the discharge opening 45, 45' can be designed, for example, as a slot following the radius or circumference of the bottleneck. Preferably, the discharge opening, e.g. as a slot, is arranged on part of the radius or circumference of the bottleneck, in particular at most on half the radius or half the circumference of the bottleneck. More preferably, the discharge opening is arranged as a slot at least on a quarter of the radius or circumference of the bottleneck. The extent of the extension of the discharge opening or slot over the radius or circumference of the bottleneck can (if the filter is not or not completely blocked) influence the proportion of exhaust gas outflow via the bypass compared to the proportion of exhaust gas outflow via the main exhaust gas flow guide 42, 42'.A different shape of the discharge opening and / or an arrangement of several discharge openings along the radius of the bottleneck at the narrowest point are also conceivable.

[0122] In the case of a bottleneck 47" arranged eccentrically in an exhaust pipe, e.g. according to Fig. 4 (c), the discharge opening 45" can be designed, e.g., as a slot following the width of the bottleneck (or as a slot following the cross-sectional contour of the bottleneck) (ie perpendicular to the plane of the drawing in Fig. 4 (c)).

[0123] The opening 45, 45', 45" of the inlet into the bypass is preferably designed so that it has at least the minimum permissible cross-section according to the standard for "Domestic heating appliances burning solid fuels" SN EN 16510-1:2023. This standard specifies that a free flow cross-section of at least 20 cm 2or at least 3% of the cross-sectional area of ​​an exhaust pipe, whichever is greater, must be unclosable. According to the standard, this free flow cross-section should preferably not be less than 1.5 cm. This means that, generally or in each of the above-mentioned designs of the bottleneck 47, 47', 47", the discharge opening 45, 45', 45" preferably has a cross-section of at least 20 cm. 2 or at least 3% of the cross-sectional area of ​​the exhaust pipe 48, 48', 48" or 49, 49', 49", whichever is greater, whereby, for safety reasons, the cross-section must not be less than 1.5 cm at any point.

[0124] The dimension of the discharge opening 45, 45', 45" in its orientation parallel to the main exhaust gas flow direction is preferably smaller than the diameter or cross-section of the bottleneck 47, 47', 47" at its narrowest point.

[0125] The bottleneck or constriction 47, 47', 47" of the embodiments shown in Fig. 4 (a), 4 (b) and 4 (c) can essentially be described as a structure consisting of three sections, 57, 58 and 59 or 57', 58' and 59' or 57", 58" and 59", i.e. a first, a second or middle and a third section, the inner cross section of which narrows, in particular e.g. conically, in the first and third sections 57 and 59 or 57' and 59' or 57" and 59" towards the middle, second section 58, 58', 58". The middle or second section 58, 58', 58" has the narrowest or smallest diameter. The third section 57, 57', 57" leads from the second section 58, 58', 58' to the filter 41, 41', 41".

[0126] According to one possible theory, in a constriction (cf. Fig. 4 (a), (b) and (c), first section 57, 57', 57" of the bottleneck 47, 47', 47") of the cross-section, a flow of a passing exhaust gas stream is accelerated, whereby the static pressure there decreases, ideally so much that the static pressure in the narrowest cross-section (cf. Fig. 4 (a), (b) and (c), second section 58, 58', 58") corresponds as much as possible to the static pressure downstream of the filter (cf. Fig. 4 (a), (b) or (c), filter 41, 41', 41" in exhaust duct section 49, 49', 49") and thus, due to the lack of a pressure gradient, no or hardly any flow through the bypass occurs. If the conditions are such that the static pressure in the narrowest cross-section is smaller than the static pressure downstream of the filter, even a negative pressure and thus a Backflow through the bypass may occur due to a low pressure gradient or negative pressure gradient (ornegative pressure), during trouble-free normal operation (i.e. at least as long as the filter 41, 41', 41" is not blocked) essentially little or no exhaust gas will flow through the bypass and thus no unfiltered exhaust gas will escape from the fireplace.

[0127] The bottleneck 47, 47', 47" is expediently designed such that the exhaust gas flow widens after the narrowest point of the bottleneck in the third section towards the filter to a cross-sectional area value which at the filter corresponds to at least twice the cross-sectional area value of the narrowest point of the bottleneck, more preferably at least four times the cross-sectional area value of the narrowest point of the bottleneck and more preferably at least eight times the cross-sectional area value of the narrowest point of the bottleneck. The widening after the narrowest point 58, 58', 58" leads to flow slowing, whereby the residence time in the filter 41, 41', 41" increases. Due to the longer residence time, the filter is more efficient, especially if it is designed as a catalyst.

[0128] The ratio of the cross-sectional area of ​​the exhaust gas flow at the narrowest point in the bottleneck to the cross-sectional area of ​​the exhaust gas flow downstream of the exhaust gas upon entry into the filter is preferably in the range of 1:2.25 to 1:25, more preferably in the range of 1:4 to 1:9. The ratio of the cross-sectional area of ​​the exhaust gas flow at the narrowest point in the bottleneck 47, 47', 47" to the cross-sectional area of ​​the exhaust gas flow upstream of the bottleneck (or at the beginning of the constriction to the bottleneck) is preferably in the range of 1:2.25 to 1:25, more preferably in the range of 1:4 to 1:9.

[0129] In the embodiment according to Fig. 4 (a), the filter 41 spans the entire diameter or cross-section of an exhaust duct 48, 49. The bypass 43 leads around the filter 41 via a lateral line 52 on the outside of the exhaust duct. The return opening 46 of the bypass 43 leads exhaust gas downstream of the filter 41 back into the exhaust duct 49.

[0130] In the embodiment according to Fig. 4 (b) and Fig. 4 (c), downstream of the filter 41', 41", the exhaust duct widens into an extension section 53', 53". The return opening 46', 46" of the bypass 43', 43" leads directly into the extension section 53', 53". The extension section 53', 53" can merge downstream into an exhaust duct 49', 49" which is identical in diameter or cross-section to the exhaust duct 48', 48" upstream of the bypass. The extension section 53', 53" can be equipped, in particular, as a separation chamber with spray and separation electrodes.

[0131] Other designs are conceivable, in particular those that do not involve any change in the external cross-section of the exhaust duct. The bypass according to the invention is of continuous construction; in particular, it has no movable flaps or other movable parts that move due to the exhaust gas flow to temporarily close the bypass and / or block the exhaust gas flow in the exhaust gas outflow direction or in the opposite direction to the exhaust gas outflow direction. Thus, the bypass is continuous and open at all times. The bypass thus expediently consists only of immovable structures.

[0132] The advantages of the bypass design are as follows: The bypass has no moving parts. Therefore, nothing can jam or stick. The bypass is permanently open. This always ensures a free minimum cross-section. Despite the bypass being permanently open, the portion of the gas flow that branches off from the main flow and flows out via the bypass is negligible or non-existent due to their design during normal operation. Preferably, the bypass and the filter are designed and coordinated in such a way that gas return occurs via the bypass during normal operation. Gas return via the bypass occurs when the exhaust gas flow, which flows out past the discharge opening 45 via the main exhaust gas flow guide 42, is able to create a suction effect on the gas volume in the bypass at the discharge opening 45.

[0133] The bypass system described with reference to Fig. 4 (a), (b) and (c) has the particular advantage that, when the catalyst is blocked and the exhaust gases must therefore flow out via the bypass, the pressure loss occurring via the bypass, i.e. from the discharge opening 45, 45', 45" to the return opening 46, 46', 46", is particularly low, so that when the exhaust gases take the alternative route via the bypass, this occurs essentially without any negative influence on the combustion in the fireplace.

[0134] An exhaust line section 40, as shown in Fig. 4 (a), can be arranged in the exhaust stream before and / or after an electrostatic particulate filter, as shown in Fig. 1 (a) or 1 (b). The bypass line 52 can be extended as far as desired, possibly even in or around the separation chamber.

[0135] The design of electrostatic particle separators with bypass solutions, whose bypass leads via a discharge opening from an exhaust duct section, as shown in Fig.

[0136] The design shown in Fig. 3 (b), Fig. 3 (c), and Fig. 3 (d) can be improved, if necessary, by integrating a throat structure with a discharge opening in the throat above the originally planned bypass discharge opening, similar to those shown in connection with Fig. 4 (a), (b), and (c). Corresponding solutions are shown in Fig. 5 (b), Fig. 5 (c), and Fig. (d). In this case, it is only necessary to arrange a constriction 47'" over an originally planned bypass discharge opening, spanning it, so that the discharge opening 45'" in the constriction communicates with the originally planned bypass discharge opening without a constriction, so that an exhaust gas flow flowing through the discharge opening 45'" at the constriction can flow to the originally planned bypass discharge opening and thus through the bypass. Fig. 5 (a) shows a variant of the solution according to Fig. 5 (c), wherein the position of the filter is arranged in the channel discharging to the particle separator instead of the channel supplying it.

[0137] A particularly preferred embodiment of a filter or gas-permeable catalyst 41" with bypass 43" for an electrostatic precipitator is shown schematically in Fig. 4 (c). The separation chamber (electrodes are omitted in this illustration) is mounted as an extension section 53" on an inlet exhaust duct section 48". A discharge exhaust duct section 49" branches off from the top side of the extension section 53". The filter or gas-permeable catalyst 41" is mounted on the inlet side in the extension section 53". The supply exhaust duct section 48" directs the exhaust gas in a meandering flow to the filter or catalyst 41" because the exhaust duct leading to the filter or catalyst 41" is curved. The bypass 43" is designed as a beak tapering toward the bypass discharge opening 45" and is made from two sheet metal parts 57" and 59".The beak 57", 59" is integrated transversely into the supply exhaust duct 48" below the filter 41" and reduces the cross section of the exhaust duct 48" to the opposite wall 58" of the exhaust duct to a constriction 47" in front of the mouth of the bypass discharge opening 45". The supply exhaust duct 48" directs the exhaust gas flow from below along the lower plate 57" of the bypass 43" along the constriction 47". After the constriction 47", the main flow guide 42" of the exhaust duct widens continuously toward the filter 41", following the upper sheet metal section 59" of the bypass 43". The exhaust flow is deflected around the mouth of the bypass discharge opening. The beak-like bypass 43" can have a width corresponding to the width of the exhaust duct 48", whereby the requirements of the standard SN EN 16510-1:2023 are preferably met. The discharge opening 45" can correspond to the width of the bypass 53" and thus of the exhaust duct 48".The deeper the beak-like bypass 43" extends into the exhaust duct 48", the more it influences the exhaust flow pattern. The discharge opening 45" is thus designed as a slot between the two tapered sheet metal parts 57", 59". A second opening, or the return opening 46", leads past the filter 41" from the bypass 43" directly into the extension section 53, thus forming an alternative outflow path, which becomes relevant when the filter 41" is blocked.

[0138] Fig. 6 shows four variants of a wood-fired stove with exhaust gas cleaning device 61, 61', 61". The exhaust gas cleaning device 61, 61' can be connected directly to the stove housing 63 with the fireplace 65 contained therein or can be spaced apart from it. In the variant according to Fig. 6 (a), the exhaust gas cleaning device 61 is integrated into the stove housing 63 or directly connected to it. In the variant according to Fig. 6 (b), the exhaust gas cleaning device 61' is connected downstream of the stove housing 63 at a distance from it. In the variant according to Fig. 6 (c), the exhaust gas cleaning device 61' is connected downstream of the stove housing 63 at a distance from it, following an intermediate heater 67. In the variant according to Fig. 6 (d), the exhaust gas cleaning device 61" is heated.In any case, the exhaust gases from the fireplace 65 are discharged through the exhaust gas cleaning device 61, 61', 61", wherein the exhaust gases flow directly from the furnace housing 63 into the exhaust gas device 61 or wherein the exhaust gases flow between the furnace housing 63 and the exhaust gas cleaning device 61', 61" through a more or less long exhaust pipe 69'.

[0139] According to the embodiment in Fig. 6 (a), the exhaust gas cleaning device can be connected directly to the furnace housing, expediently by placing the exhaust gas cleaning device on the furnace housing. In the contact area between the two units, a flow opening can be provided, which essentially corresponds to the cross-sectional dimensions of the fireplace. The transition from the furnace chamber to the separation chamber can thus be designed without an exhaust pipe and, if necessary, without a flow bottleneck. If the separation chamber is arranged above the fireplace 65 and the counter electrodes defining the separation chamber are arranged, for example, according to the inner circumferential contour of the furnace walls and / or within this contour, a combined chamber for combustion (in the lower area) and cleaning (in the upper area) is created, which offers the advantage that solid particles deposited on the electrodes can fall back into the fireplace.

[0140] The exhaust gas purification device 61, 61', 61" includes the described electrostatic particle filter and preferably an additional filter with a bypass, wherein, for example, the filter and bypass can be integrated into the exhaust pipe as an exhaust line section (as shown in Fig. 4 (a)) upstream or downstream of the separation chamber. The filter can be a gas-permeable catalyst that converts unwanted gases - in particular, for example, carbon monoxide (CO) into carbon dioxide (CO2). In arrangements in which the exhaust gas purification device 61 is located far enough downstream of the fireplace that the exhaust gases cool down so much by the time they reach the exhaust gas purification device that the exhaust gas purification device as a whole or parts thereof, such as the additional filter or catalyst, no longer function reliably, a heater 67 can be interposed between the furnace housing 63 and the exhaust gas purification device 61, as shown in Fig. 6 (c), which heater heats the exhaust gases to a desired temperature.This heater 67 can be arranged, for example, on or in the exhaust pipe 69', in particular, for example, be integrated in the exhaust pipe 69' and / or comprise the exhaust pipe.

[0141] Alternatively, filters can be heated directly, e.g., by equipping the filters with a heating element or by heating them via a heating element. This is particularly useful when a filter is configured as an exhaust gas catalyst. For example, as shown in Fig. 7, a filter 83 installed in an exhaust duct region 81 can be in contact with a heating element.

[0142] Furthermore, the electrodes of an electrostatic particle separator can also be heated directly if necessary by equipping the electrodes with heating elements. Wall elements of a separation chamber 91 of an electrostatic particle separator can be designed, for example, as electrodes 93, and equipped with integrated heating elements 95, as shown in Fig. 8. Heating the electrodes or the walls or the separation chamber itself reduces the condensation of tar in the separation chamber and in particular on the electrodes. Since tar deposits on the electrodes can disrupt electrostatic particle separation and tar deposits are often difficult to remove, heating the electrodes in the separation chamber or the walls or the separation chamber can be advantageous. Due to the reduced tar deposit formation during heating, the time interval until the next mechanical cleaning of the exhaust gas purification system can be increased.

[0143] Heating the exhaust gas shortly before entering an exhaust gas purification device (Fig. 6 (c)), heating an exhaust gas purification device (Fig. 6 (d)), heating a filter (Fig. 7), especially if it is designed as a gas catalyst, or heating the electrodes contained in a separation chamber of an exhaust gas purification device (Fig. 8) can be particularly useful when the exhaust gas purification device is relatively far away from the furnace housing 63. Due to the distance that the exhaust gas has to travel from the furnace to the exhaust gas purification device, it takes too long after ignition for the exhaust gas itself to heat up, which can result in the cleaning effect of the exhaust gas purification device only becoming effective with a delay. By heating, relevant exhaust gas purification device areas can be brought to an adequate operating temperature more quickly and / or maintained more effectively.Depending on the size, type and arrangement of the heating system and exhaust gas purification system, heating, in particular one of the heating types shown or a combination, may be useful.

[0144] Alternatively, it may be possible to use heating elements to warm up the exhaust system or parts of it before lighting the fire.

[0145] To the extent that the exhaust gas purification device creates an expansion of the exhaust gas duct in sections, the exhaust gas purification device can be equipped with a cleaning device 121 and / or a type of retention container or retention chamber 127, as shown in Fig. 9 (a) and (b). Here, the accumulated mineral dust can be loosened by tapping or other mechanical action, such as during cleaning with a cleaning device 121 installed in the separation chamber. The loosened dust falls into the retention container or chamber 127 and is caught and retained thereby. A retention chamber 127 is created, for example, in an exhaust gas device according to Fig. 1 if, as shown in Fig. 9, an exhaust gas duct section 8 leading from below into the separation chamber 15 has an extension 125 projecting into the separation chamber 15.The cleaning device 121 can be designed, for example, as a grid or cage, in particular as a cylindrical cage, and can be made of metal, for example. The grid or cage 121 can be moved mechanically relative to the counter-electrode surfaces in order to mechanically remove any deposits from the counter-electrode surfaces. The cleaning device shown in Fig. 9 (a) and (b) shows a cylindrically shaped cage. The dust can be vacuumed out of the retention chamber 127 in the cold state during regular cleaning (by the chimney sweep), for example using an ash vacuum, or removed in another way. It is advantageous if a service hatch 131 is provided for cleaning and other servicing work, which service hatch can conveniently be closed with a hatch door 133.

[0146] While specific embodiments have been described above, it is obvious that different combinations of the embodiments shown may be used, provided that the embodiments are not mutually exclusive.

[0147] While the invention has been described above with reference to specific embodiments, it is obvious that changes, modifications, variations and combinations may be made without departing from the spirit of the invention.

[0148] LIST OF REFERENCE SYMBOLS:

[0149] 1, 1' - 1'''''' Electrostatic Particle Separator (Separator)

[0150] 6 Exhaust gas inlet of the separator

[0151] 7, 7 Exhaust gas outlet opening of the separator

[0152] 8 Exhaust duct section or inlet-side connection of the separator to the exhaust duct

[0153] 9, 9' Exhaust duct section or outlet-side connection of the separator to the exhaust duct

[0154] 11, 11' Electrode, this serves in particular as a spray electrode

[0155] 13 Counter electrode, this serves in particular as a separation electrode

[0156] 14 wall areas aligned transversely to the exhaust gas flow direction, can also serve as a separation electrode

[0157] 15, 15' separation room

[0158] 17, 17' insulator

[0159] 21, 21 / Electrode, this serves particularly as a spray electrode

[0160] 23, 23'- 23' Counter electrode, this serves in particular as a separation electrode

[0161] 25 Additional walls or counter electrode walls with catalytic surfaces

[0162] 27 counter electrode segments

[0163] 31, 31' filter or gas permeable catalyst

[0164] 33, 33'- 33' Bypass

[0165] 40, 40', 40' exhaust pipe section

[0166] 41, 41', 41" filter or gas permeable catalyst

[0167] 42, 42', 42" main exhaust flow

[0168] 43, 43', 43" Bypass

[0169] 44, 44', 44" Step or Shoulder 45, 45', 45", 45' Discharge Opening

[0170] 46, 46', 46' return opening

[0171] 47, 47, 47", 47" bottleneck, also called constriction or narrowing

[0172] 48, 48', 48' Exhaust pipe section or exhaust pipe connection located upstream of the exhaust gas

[0173] 49, 49', 49" Downstream exhaust pipe section or exhaust pipe connection

[0174] 51, 51', 51" filter entry point

[0175] 52 Lateral bypass line

[0176] 53', 53" extension section

[0177] 55', 55' perimeter of the extension section

[0178] 57, 57, 57' First section of a bottleneck structure

[0179] 58, 58', 58" Second or middle section of the bottleneck structure

[0180] 59, 59', 59' Third section of the bottleneck structure

[0181] 61, 61', 61 exhaust gas purification device

[0182] 63 Furnace housing

[0183] 65 fireplace

[0184] 67 stokers

[0185] 69, 69' exhaust pipe

[0186] 71 Heating element for heating the exhaust gas purification system

[0187] 81 exhaust duct

[0188] 83 Filters, in particular designed as exhaust gas catalysts

[0189] 85 Heating element for heating the filter

[0190] 91 Separation chamber of an electrostatic particle separator

[0191] 93 Counter electrode 95 Heating element for heating the counter electrode

[0192] 101, 101' Electrostatic Particle Separator (Separator)

[0193] 121 separation facility

[0194] 123 Dust accumulation

[0195] 125 Exhaust duct extension (dust collector)

[0196] 127 retention area

[0197] 131 Service hatch

[0198] 133 hatch door

[0199] 135 door handle

Claims

CLAIMS 1. Flue gas purification device (1, 1', 1", 1'", 1"", 1"'", 1""") for purifying flue gases from solid fuel combustion systems, such as from wood-fired fireplaces (65), comprising at least one separation chamber (15, 15'), wherein in the separation chamber (15) at least one first electrode (11, 11', 21, 21'), which is preferably designed as a spray electrode, and at least one second electrode (13, 14, 23, 23', 23", 23"), which is designed as a counter electrode, are arranged, wherein the at least one first electrode (11, 11', 21, 21') is surrounded by the at least one second electrode (13, 14, 23, 23', 23", 23"), and wherein the separation chamber (15, 15') is for the purpose Passage of an exhaust gas stream has an exhaust gas inlet opening (6) and an exhaust gas outlet opening (7, 7'), characterized in that at least one of the electrodes is catalytic, ie for example made of catalytic material or is catalytically coated.

2. Exhaust gas purification device according to the preceding claim, characterized in that the separation chamber (15) has an equally large or an enlarged passage cross-section compared to the exhaust gas inlet opening (6), wherein preferably the ratio of the cross-section of the separation chamber (15) to the cross-section of the supplying exhaust gas duct (8) is 1.1:1 or more, more preferably in the range from 1.2:1 to 20:1 and particularly preferably in the range from 1.2:1 to 10:

1.

3. Exhaust gas purification device according to one of the preceding claims, characterized in that the at least one first electrode (11, 11', 21, 21') is surrounded, in particular e.g. encircled, by the at least one second electrode, in that the at least one second electrode (13, 14, 23, 23', 23", 23") is designed as a lining or wall of the separation chamber (15, 15'), wherein preferably a minimum width of the separation chamber of at least 50 mm, preferably at least 60 mm, more preferably at least 80 mm, and particularly preferably at least 100 mm is not undercut.

4. Exhaust gas purification device according to one of the preceding claims, characterized in that the at least one first electrode is designed as a plate electrode and is arranged such that the surface normal of the plate electrode is aligned substantially parallel to the exhaust gas flow.

5. Exhaust gas purification device according to one of the preceding claims, characterized in that the at least one first electrode is designed as a rod electrode and is arranged such that the rod electrode and the exhaust gas flow are aligned substantially parallel.

6. Exhaust gas purification device according to one of the preceding claims, characterized in that at least the at least one second electrode or the counter electrode (13, 14, 23, 23', 23", 23") is catalytic.

7. Exhaust gas purification device according to one of the preceding claims, characterized in that at least the at least one first electrode or the spray electrode (11, 11', 21, 21') is catalytically designed, or that the at least one first electrode or the spray electrode and the at least one second electrode or the counter electrode are catalytically designed.

8. Exhaust gas purification device according to one of the preceding claims, characterized in that the at least one first electrode or the spray electrode (11, 11', 21, 21') is equipped with a voltage source, preferably a voltage source in the high voltage range, in particular e.g. in the range of 3 kV - 100 kV, and / or that the at least one second electrode or the counter electrode (13, 14, 23, 23', 23", 23") is grounded.

9. Exhaust gas purification device according to one of the preceding claims, characterized in that the catalytically designed electrode or electrodes contain materials, in particular have surfaces made of materials, selected from the group consisting of precious metals, in particular gold, Platinum and palladium, other metals, ceramic materials, in particular oxides, e.g. cerium dioxide (CeO2), vanadium pentoxide (V2O5), iron(III) oxide (Fe2O3), lanthanum oxide (La2O3), titanium dioxide (TiO2) and zirconium dioxide (ZrO2), salts, in particular potassium salts (K2CO3) and combinations thereof.

10. Exhaust gas purification device according to one of the preceding claims, characterized in that the catalytically designed electrode or electrodes, in particular their surfaces, are made of foam materials, e.g. ceramic foam, metal foam or polymeric foams, which themselves have a catalytic effect or have a catalytically active coating, wherein foam ceramics, e.g. essentially consisting of the group comprising silicon carbide, aluminum oxide, cordierite, zirconium oxide or combinations thereof, or metallic foam, e.g. essentially consisting of stainless steel or FeCrAl, are preferred as the foam materials.

11. Exhaust gas purification device according to one of the preceding claims, characterized in that a filter (31, 31', 41, 41', 41") is arranged upstream and / or downstream of the separation chamber (15) in the exhaust gas flow and a bypass (33, 33', 33", 33'", 43, 43', 43") is guided around the filter (31, 31', 41, 41', 41") or around the filter (31, 31') and the separation chamber (15), wherein an upstream filter (31') is particularly preferred.

12. Exhaust gas purification device according to one of the preceding claims, characterized in that a cleaning device (121) and / or a retention container or retention chamber (127) for dedusting at least the counter electrode are provided in the separation chamber (15).

13. Exhaust gas purification device (1'", 1''', 1''''', 1'''''), in particular for purifying exhaust gases from solid fuel combustion systems, such as from wood-fired fireplaces (65), comprising a separation chamber (15, 15'), wherein in the separation chamber (15, 15') at least one first electrode (11, 11'), which is preferably designed as a spray electrode, and at least one second electrode (13, 14), which is designed as a counter electrode, are arranged, wherein the separation chamber (15, 15'), for the purpose of passing an exhaust gas flow, Exhaust gas inlet opening (6) and an exhaust gas outlet opening (7, 7'), preferably according to one of claims 1-12, characterized in that the exhaust gas purification device is equipped with at least one filter (31, 31', 41, 41', 41") and a bypass (33, 33', 33", 33'", 43, 43', 43"), in particular a bypass around at least the at least one filter.

14. Exhaust gas purification device according to the preceding claim 13, characterized in that the bypass leads from a bottleneck (47) of the exhaust gas flow, in particular from a bottleneck in an exhaust gas duct section (8) leading to the exhaust gas inlet opening (6) or in an exhaust gas duct section (9, 9') leading away from the exhaust gas outlet opening (7, 7'), in particular from a point or passage (58, 58', 58") of the smallest cross-section of the bottleneck (47, 47', 47", 47'").

15. Exhaust gas purification device according to the preceding claim 14, characterized in that the bottleneck (47, 47', 47") is essentially formed by two mutually directed, converging narrowing structures (57, 57', 57" and 59, 59', 59"), which, where they unite, expediently form a point or passage (58, 58', 58") of the smallest cross-section of the bottleneck (47, 47', 47").

16. Exhaust gas purification device according to one of the preceding claims 14 or 15, characterized in that the bottleneck (47") is arranged eccentrically with respect to the filter (41"), wherein the bottleneck (47") has, at its location or passage (58, 58', 58") of the smallest cross section, two opposite side regions, the first side region on the maximally eccentric side and the second side region on the minimally eccentric side of the smallest cross section with respect to the filter (41"), wherein the bypass (43") leads essentially from the minimally eccentric side region.

17. Exhaust gas purification device according to one of the preceding claims 14 to 16, characterized in that the exhaust gas duct section located upstream of the bottleneck is designed such that the bottleneck is inclined is flowed against, in particular so that the exhaust gas flow in the bottleneck (47") is deflected via an exhaust opening (45") of the bypass.

18. Exhaust gas purification device according to one of the preceding claims 13 to 17, characterized in that the filter (31, 31') is arranged upstream and / or downstream of the separation chamber (15, 15') in the exhaust gas flow and the bypass (33, 33', 33", 33'") is guided around the filter (31, 31', 41, 41', 41") or around the filter (31, 31') and the separation chamber (15), wherein an upstream filter (31') is particularly preferred.

19. Exhaust gas purification device according to one of the preceding claims 13 to 18, characterized in that the filter (31, 31', 41) is a gas-permeable catalyst.

20. Solid fuel combustion plant, in particular wood combustion plant, comprising a furnace housing (63) with a fireplace (65) and an exhaust gas purification device (61, 61') in the exhaust gas stream of the fireplace according to one of the preceding claims 1-19.

21. Solid fuel combustion plant according to the preceding claim 20, characterized in that the separation chamber (15) has an expanded passage cross-section compared to an exhaust gas duct for the exhaust gas flow which is fed from the combustion plant to the exhaust gas purification device via the exhaust gas inlet opening (6).

22. Solid fuel combustion plant according to the preceding claim 20, characterized in that the exhaust gas purification device (61) is integrated in the furnace housing (63) or is placed on the furnace housing (63).

23. Solid fuel combustion plant according to one of the preceding claims 20 to 22, characterized in that the furnace housing (63) and the exhaust gas purification device (61, 61') are matched to one another and designed in such a way that during operation of the plant the temperature of at least one of the catalytically designed electrodes (11, 11', 21, 21', 13, 14, 23, 23', 23", 23"), preferably at least one catalytically designed counter electrode (13, 14, 23, 23', 23", 23"), is a predetermined operating temperature is set or can be set at which particles, in particular soot or tar particles, which are deposited on the at least one catalytically designed electrode during operation of the system can burn off.

24. Solid fuel combustion plant according to the preceding claim 23, characterized in that the furnace housing (63) and exhaust gas purification device (61, 61') are matched to one another and designed such that the at least one of the catalytically designed electrodes (11, 11', 21, 21', 13, 14, 23, 23', 23", 23") can be kept at the aforementioned operating temperature due to the thermal energy of the exhaust gas flow which flows from the combustion plant during operation.

25. Exhaust gas purification device according to one of claims 1-19 or solid fuel combustion plant according to one of claims 20-24, characterized in that the exhaust gas purification device or the solid fuel combustion plant is equipped with a heater for heating the catalytically designed electrodes (93), the at least one filter (83), the separation chamber and / or the exhaust gas purification device (61"), at least during ignition, so that an operating temperature of the respective component which is higher than room temperature can be reached as quickly as possible after ignition.

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