DE19636434A1 - Soot particle removal from diesel exhaust gases - Google Patents

Abstract

The process removes soot particles from exhaust gases from heating oil or diesel fuel combustion, holding back the particles by direct contact with a cleaning fluid (11), e.g. paraffin. Also claimed is a waste gas cleaner esp. for vehicles. Pref. thin paraffin oil, such as Paraffinum subliquidum DAB 9 (Deutsches Arznei-Buch or German pharmacopoeia) is used. A first cleaning stage (4) pref. contacts the waste gas flow with paraffin to remove soot particles.

Description

The invention relates to a method and a device, in particular for power vehicles for removing soot particles from the combustion of heating oil or exhaust gases generated by diesel fuel. For the separation of soot particles from exhaust gases, for example from diesel engines or heating systems several options available. In conventional gas filter systems for example, a dry filter turned on in the gas stream. Such filters are in principle porous materials, such as wire mesh, paper fleece, etc., that the Allow flow through the exhaust gas and the soot particles back in the exhaust gas to keep. The disadvantage of such filter systems is that the filters change after some Add time and must be replaced with new or cleaned filters sen.

EP 0 616 833 A1 describes a soot filter for diesel engines with several next to one another of the tubular filter candles arranged in a filter space. The Exhaust gas passes through the wall from the outside inwards, the Soot deposits on the outer pipe wall. After the formation of a soot layer, this becomes burned with a burner. In one described in EP 0 583 507 B1 Soot filters are used to regenerate the filter cartridges by using an external one Hot gas generator connected to the soot filter and the filter candles with hot be flushed with gas. Wet filtering methods are also known in which the Gas is passed through a liquid bath.

The object of the invention is an alternative and improved method and vorzu such a device for removing soot particles from exhaust gases beat.  

This object is achieved by a method according to claim 1 and an apparatus solved according to claim 12. In the process according to the invention, soot exhaust gases containing particles brought into intimate contact with liquid paraffin. It has been shown that paraffin has a great affinity for soot particles, and filter them out of a gas stream with very high efficiency tern can. Paraffinum subliquidum (DAB 9) advantageously becomes a thin liquid paraffin used. However, one does not become uncomfortable for cost reasons depends on highly cleaned, for the medical or cosmetic area use suitable paraffin, but technical, with less Degree of purity. According to the teaching given in claim 3, soot Particles loaded paraffin transferred into a quiet zone, in which the soot particles can settle through sedimentation. In a second, downstream The cleaning stage is entrained by the paraffin entrained by the exhaust gas flow Filter media retained. Preferably in the first cleaning stage Paraffin mist or a paraffin aerosol generated. In this way the effective surface area of the paraffin is significantly increased and thus a very high cleaning efficiency achieved. The device of claim 5 has the The advantage that the finest paraffin particles or droplets can be produced. The effective surface and thus the cleaning efficiency is again increased. Another advantageous possibility in the first cleaning stage To achieve separation of the soot particles is that the exhaust gas flow through a passage opening and wetted with a paraffin film Endless belt is guided. The endless belt becomes transverse to the direction of flow of the exhaust gas moves. Due to the design as an endless belt passes through Movement path of the endless belt the exhaust gas flow at least twice, näm Lich on an upstream and a distance downstream downward point. The endless belt preferably has a very large one Surface so that the paraffin film on its surface is a has a correspondingly large effective surface. By the movement of the endless bandes it is possible that the paraffin film in a relatively simple manner  can be renewed continuously. An advantageous way of renewing tion of the paraffin film is specified in claim 7. Then the Bewe dives part of the continuous belt in a paraffin bath. By the ent The paraffin film is at least partially extracted from the flowing exhaust gas Continuous belt blown out. This blowout takes place to a certain extent measure the atomization of the paraffin film instead, which means an additional cleaning causes.

The in the endless belt cleaning process as well as in the atomization ver paraffin portions entrained by the gas flow downstream are moved forward geous way by at least one transverse to the flow direction and preferred wise approximately vertically arranged flat filter element (An Proverbs 8). The filter elements can be conventional for the one in question The purpose is to use suitable nets, braids, knitted fabrics, fleeces etc.

According to claim 9, there is an advantageous embodiment of the fiction method according to the fact that a third Reini supply stage in which an exhaust gas purification with the help of a catalyst is carried out. In this way, an almost complete cleaning is a from a combustion of diesel fuel or heating oil possible. As is well known, catalysts have one for the purpose in question very large, with a catalytic mass and with the exhaust gas in Contact surface. This surface would only be inaccurate pre-cleaning, i.e. incomplete removal of soot particles the exhaust gas flow fail very quickly because the catalytic Surface would be covered with soot particles and thereby inactivated.

According to claim 10 it is provided that those accumulating in the quiet zone Soot particles are removed at certain maintenance intervals. This can ge according to claim 11 in an advantageous manner that the sediments  tion of the soot particles in a container designed as an interchangeable cartridge he follows.

The features essential to the invention of a device according to the invention are specified in claim 12. An advantage of the device according to the invention lies for example in that the individual cleaning sections or cleaning chambers housed in a confined space in a common housing can be without having to between the individual cleaning sections agile connecting cables etc. would be necessary. The advantage of the Ausgestal device according to claim 13 is that between the individual cleaning sections no increase in flow velocity takes place, so that in Paraffin droplets entrained in the exhaust gas stream have enough time to go down sink. In an advantageous embodiment, the Invention arranged a cleaning device in the form of a spray device. This spray device is preferably at least one high-frequency piezozer dust, with the very fine liquid mist and thus very large effective Surfaces can be created. The spray device is preferably in upper area, especially on the ceiling of the main cleaning chamber arranged. This ensures that the direction of spray is essentially after below, d. H. So in the operating state transverse to the flow direction of the exhaust gas he follows.

The advantage of the measure according to claim 18 is that the mouth Opening the supply line like an overflow to keep a maxi paint liquid levels in the main cleaning chamber can serve. The Sucking in air or an exhaust gas / air mixture from the main cleaning system mer is prevented that the pump the cleaning liquid from a Subtracts reservoir, which in turn from the overflow mentioned Main cleaning chamber is fed.

The invention will now be illustrated with reference to the accompanying drawings Exemplary embodiments explained in more detail. It shows

Fig. 1 shows a first embodiment of a device according to the invention in a perspective schematic representation, and

Fig. 2 is a perspective schematic representation of a further embodiment of the inventions.

The exhaust gas purifying devices according to Fig. 1 and 2 have a housing 1, which is generally adapted to the particular installation conditions. For example, in the case of an exhaust gas cleaning device provided for a motor vehicle, it may have the shape of a circular or oval cylinder, etc. An inlet 2 and an outlet 3 are provided on the front of the housing. Inlet and outlet are also shown only schematically. Their actual design can be very diverse, for example in the form of a cone opening towards the respective end face of the housing.

The housing 1 is subdivided into three sections, the housing section closest to the inlet 2 forming a main cleaning chamber 4 , the section adjoining it a post-cleaning chamber 5 and finally the last section where the outlet 3 is located, a catalyst chamber 6 . The longitudinal axis 7 of the housing 1 runs horizontally when installed or in the operating state in the present case. A gas flow entering the housing through the inlet 2 and exiting through the inlet 3 therefore has a flow direction running approximately in the direction of the longitudinal axis 7 .

In the top wall 8 of the main cleaning chamber 4 there is an opening through which a spray device projects into the interior of the main cleaning chamber. The arrangement of the spray device can be done in a variety of ways. The spray device can e.g. B. can also be arranged completely within the main cleaning chamber. A piezo high-frequency atomizer 9 is preferably used as the spray device.

The main cleaning chamber is filled up to a level 10 with liquid paraffin in the manner of paraffin and subliquidum (DAB 9). In a height level 10 corresponding position, an overflow opening 13 is arranged on a side wall of the main cleaning supply chamber 4 , which is connected to a supply line 14 . The supply line 14 is fluidly connected to the piezo high-frequency atomizer 9 . A supply container 15 for paraffin is interposed in the supply line 14 . Between the Vorratsbe container 15 and the piezo high-frequency atomizer 9 , a pump, preferably an electrically operated pump 16, is arranged in the supply line 14 .

In the post-cleaning chamber, several filter elements 17 designed in the manner of filter plates are spaced approximately parallel to one another and arranged approximately transversely to the longitudinal axis 7 or to the flow direction. The filter elements 17 can e.g. B. contain one or more layers of mesh, knitted fabrics, knitted fabrics or nonwovens made of tall or plastic. It is crucial that they can perform the desired function, as explained below.

The catalyst chamber 6 connects to the post-cleaning chamber 5 . This chamber is not absolutely necessary. However, if a complete exhaust gas purification, ie also a reduction of gaseous pollutants, is to be achieved, it is advisable to provide such a chamber and to equip it with a conventional exhaust gas catalyst. The bottom 18 of the catalyst chamber 6 is preferably arranged above the height level 10 . In this way, the paraffin present in the main cleaning chamber 4 and also in the post-cleaning chamber 5 cannot get into the catalyst chamber 6 . In the case of installation in motor vehicles, further measures can be provided, such as a baffle (not shown) between the post-cleaning chamber 5 and the catalyst chamber 6 in order to prevent the paraffin from spilling over into the catalyst chamber. In the schematic illustrations of FIGS. 1 and 2, the bottom is the Nachreinigungskammer 5 is inclined 19 to the main cleaning chamber 4. Such a configuration is not absolutely necessary, but it can offer certain advantages (see below).

On the underside of the housing 1 there is a container designed in the manner of an exchangeable cartridge 20 . Except for the end face 24 of the replaceable cartridge facing the outlet 3 , the remaining side walls of the cartridge are aligned with the side walls of the housing 1 . The interchangeable cartridge 20 has a sloping Mittelab section 25 , the inclination of which corresponds to that of the bottom 19 of the post-cleaning chamber 6 . The with the bottom 23 and the bottom 19 of the main cleaning chamber 5 and the post-cleaning chamber 6 in overlapping top of the cartridge 20 is open. The floors mentioned are provided with a plurality of passage openings 26 , so that the interior of the exchangeable ink cartridge 20 is in fluid communication with the interior of both the main cleaning chamber 4 and the post-cleaning chamber 5 . Therefore, the replaceable cartridge 20 is when a paraffin is in the main cleaning chamber 4 and possibly also in the Nachreinigungskammer 5 12, at least completely filled in the area of chambers 4 and 5 with paraffin. 11

. The operation of an exhaust gas purifying device of the invention shown in Figure 1 will now be explained in more detail below: The housing through the inlet 2 in the exhaust gas flowing Ge 1 is first reacted with a fine mist paraffin in intimate contact. The degree of atomization of the paraffin or the size of the paraffin droplets generated depends on the respective cleaning tasks. However, the finer the atomization, the larger the effective surface and the more efficient the cleaning effect. The soot particles contained in the exhaust gas have a high affinity for paraffin and are absorbed in the paraffin droplets and probably also held on their surface. The paraffin droplets loaded with soot particles sink due to gravity. In order to prevent or reduce the entrainment of paraffin droplets in the exhaust gas stream, it is advantageous if the flow cross section of the housing 1 increases with respect to the inlet 2 . In this way it is ensured that the main part of the paraffin droplets in the main cleaning chamber 4 sinks down into the paraffin bath 12 present there. The fact that the passage opening 26 is formed in the bottoms 23 and 19 , the soot particles can sink into the interchangeable cartridge and accumulate there. Agglomeration effects are also likely to play a role here. In the case of motor vehicles, the sedimentation process can be partially disturbed by shocks and vibrations. Sedimentation can, however, take place at least during the downtimes of the vehicle. Once arrived in the replaceable cartridge 20 Rußpar but are retained in spite of turbulence within the paraffin bath 12 selkartusche in the Wech 20 Tikel.

Paraffin droplets carried in the exhaust gas stream are retained in the post-cleaning chamber 5 by the filter elements 17 present there. Due to their vertical arrangement, the paraffin retained there can flow downwards. The filter elements 17 are coated with a paraffin film in the operating state, which absorbs any soot particles still present in the exhaust gas stream. The soot particles can, as in the main cleaning chamber 4 , pass through the through openings 26 in the bottom 19 of the post-cleaning chamber 5 into the exchangeable cartridge 20 . Since the arranged in the area of the Nachreinigungskam 5 central section 25 of the replaceable cartridge 20 is inclined in the direction of the main cleaning chamber 4 , the soot particles can as it were on a slide in the main cleaning chamber 4 assigned area of the replaceable cartridge, which may have a larger storage volume.

The level 10 of the paraffin bath 12 is kept constant by this overflow opening 13 . The overflowing paraffin 11 is collected in the storage container 15 . From this reservoir 16 paraffin is pumped off by the pump and conveyed to the piezo high-frequency atomizer 9 . The amount of paraffin supplied to the atomizer 9 is preferably regulated as a function of the load. So it is conceivable, for example, that an atomizer works with lower atomizing power in the low load range and a second atomizer with higher power is switched on in the high load range. In the case of motor vehicles, control as a function of the clock frequency of the fuel injection is also conceivable.

To replace the interchangeable cartridge, the paraffin 11 located in the housing 1 and in the interchangeable cartridge is first released from a closable drain opening 27 arranged at the lowest point of the interchangeable cartridge 20 . The replaceable cartridge 20 is then removed from the housing 1 , for example in the direction of the arrow 28 , and exchanged for a new one.

The device shown in FIG. 2 differs from that according to FIG. 1 only in another way of bringing the paraffin into contact with the exhaust gas stream in the main cleaning chamber 4 . In the chamber 4 , an endless belt 33 that can be penetrated by the exhaust gas flow is guided over two cylindrical rollers 35 , 36 in the manner of a caterpillar track. The roller 35 is arranged in the upper part and the roller 36 in the lower part of the main cleaning chamber 4 . Both rollers are rotatable about an axis of rotation 37 , 38 , the axes of rotation being arranged in a common vertical plane running parallel to the flow direction of the exhaust gas or transverse to the longitudinal axis 7 and parallel to one another. One of the two rollers 35 , 36 can be driven, for example, by a turbine wheel arranged within the space delimited by the endless belt 33 and the rollers 35 , 36 or, if appropriate, by an electric motor arranged on the outside of the housing 1 . The Wal zen 35 , 36 and the endless belt 33 extend practically over the entire width of the interior of the main cleaning chamber 4th The endless belt 33 be made of a flexible band with several passage openings, for example made of a metal or plastic mesh or the like. In the operating state, it is constantly wetted with paraffin or coated with a paraffin film since the lower roller 36 is immersed in the paraffin bath 12 .

In this embodiment, a fine distribution of the paraffin is achieved in a different way than that in accordance with FIG. 1. A fabric or a structure of a similar type has a very large surface. During operation, during which the endless belt moves in the direction of arrow 34 , this surface is always wetted with paraffin or covered with a paraffin film. The gas flowing in through inlet 2 first strikes the side of the endless belt facing the inlet and flows through it. In this flow-through process, soot particles are absorbed by the paraffin on the endless belt. Part of the paraffin is torn off the endless belt, forming fine droplets or a mist. The resulting paraffin droplets can also filter out soot particles from the exhaust gas stream. Due to the continuous circulation of the endless belt 33 through the paraffin bath in the main cleaning chamber 4 , the paraffin film on the endless belt 33 is constantly renewed. Any soot particles on it are washed off when the belt passes through the paraffin bath. As already explained above, the particles, supported by agglomeration effects, pass through the through openings 26 in the bottom 23 into the exchangeable cartridge 20 . Paraffin droplets entrained by the exhaust gas stream are filtered out in the post-cleaning chamber 5 in the manner described above.

Reference list

1 housing
2 inlet
3 outlet
4 main cleaning chamber
5 post-cleaning chamber
6 catalyst chamber
7 longitudinal axis
8 ceiling wall
9 piezo high frequency atomizers
10 height level
11 paraffin
12 paraffin bath
13 overflow opening
14 supply line
15 storage containers
16 pump
17 filter element
18 bottom
19 floor
20 exchangeable cartridges
23 floor
24 end face
25 middle section
26 passage opening
27 drain opening
28 arrow
33 endless belt
34 arrow
35 roller
36 roller
37 axis of rotation
38 axis of rotation

Claims (25)

1. Method for removing soot particles from the combustion of heating Exhaust gases produced in oil or diesel fuel, in which the exhaust gases with a the soot particles retaining cleaning liquid in intimate contact be brought, using paraffin as the cleaning liquid. 2. The method according to claim 1, characterized, that low viscosity paraffin like Paraffinum subliquidum (DAB 9) ver is applied. 3. The method according to any one of claims 1 or 2, characterized by

• a first purification stage in which the exhaust gas stream is brought into contact with the paraffin, soot particles being taken up by the paraffin and the paraffin thus loaded with soot particles being transferred to a rest zone in which the soot particles settle by sedimentation,
• - And a second cleaning stage, in which paraffin entrained by the exhaust gas stream is retained and fed to the rest zone and the first cleaning stage.

4. The method according to claim 3, characterized, that produces a paraffin mist or aerosol in the first cleaning stage becomes.   5. The method according to claim 4, characterized, that the paraffin mist or the paraffin aerosol with the help of at least one Piezo high-frequency atomizer is generated. 6. The method according to claim 3, marked by a cleaning of the exhaust gas in the first cleaning stage such that the Ab gas flow through a passage opening and with a paraffin film-wetted endless belt is guided, the endless belt transverse to the stream direction of the exhaust gas is moved. 7. The method according to claim 6, characterized, that the trajectory of the endless belt is partially within a paraffin baths runs. 8. The method according to any one of claims 3-7, characterized, that the separation of paraffins entrained by the gas stream in the second Cleaning stage by at least one transverse to the direction of flow and before preferably approximately vertically arranged flat filter element. 9. The method according to any one of claims 3-8, characterized, that a third cleaning stage follows the second cleaning stage, in which pollutants are reduced with the help of a catalytic converter. 10. The method according to any one of claims 3-9, characterized,  that the soot particles accumulating in the quiet zone are removed on a regular basis be removed. 11. The method according to claim 10, characterized, that the sedimentation of the soot particles in a replaceable cartridge formed container takes place. 12. Exhaust gas purification device, in particular for motor vehicles, for removing soot particles from exhaust gases formed during the combustion of heating oil or diesel fuel, characterized by

• - A main cleaning chamber ( 4 ) in which a cleaning device for contacting a cleaning liquid ( 11 ) with the Abga sen is arranged,
• Complete a below the main cleaning chamber (4) arranged sediments tationsbehälter (20), which is separated by a plurality of passage openings (26) facing the bottom (23) of the main cleaning chamber (4), wherein tationsbehälter in the operating state the exhaust gas purifying apparatus of the sediments (20) - and the main cleaning chamber ( 4 ) is partially flooded with a cleaning liquid bath ( 12 ) and
• - One - seen in the flow direction of the exhaust gases - downstream after cleaning chamber ( 5 ) with at least one filter element ( 17 ) to filter out from the main cleaning chamber ( 4 ) discharged cleaning liquid speed.

13. Exhaust gas cleaning device according to claim 12, characterized in that the post-cleaning chamber ( 5 ) immediately and without a narrowing of the flow cross section to the main cleaning chamber ( 4 ). 14. Exhaust gas purification device according to claim 12 or 13, characterized, that the cleaning device is a spray device. 15. Exhaust gas purification device according to claim 14, characterized, that the spray device has at least one piezo high-frequency atomizer includes. 16. Exhaust gas purification device according to claim 14 or 15, characterized in that the spray device in the upper region, preferably on the ceiling wall ( 8 ) of the main cleaning chamber ( 4 ) is arranged. 17. An exhaust purification device according to any one of claims 14-16, characterized by a lower to the, to the bottom (23) of the main cleaning chamber (4) gren collapsing and accumulated in the operating state with a Reinigungsflüssigkeitsbad (12) area of the main cleaning chamber (4) opens and a pump ( 16 ) with the spray device fluidly connected supply line ( 14 ). 18. Exhaust gas purification device according to claim 17, characterized in that on the suction side to the pump ( 16 ) a reservoir ( 15 ) for cleaning liquid ( 11 ) is arranged in the supply line ( 14 ). 19. Exhaust gas purification device according to one of claims 12-18, characterized in that the at least one filter element ( 17 ) is a vertical or standing in Betriebszu arranged transversely to the flow direction and substantially covering the entire flow cross-section filter plate. 20. Exhaust gas purification device according to claim 19, characterized, that the filter plate consists essentially of a preferably multilayer Net, a knitted fabric, a knitted fabric or a fleece made of a wire or Thread is made of metal or plastic. 21. Exhaust gas purification device according to one of claims 12-20, characterized in that the sedimentation container ( 20 ) covers the bottom surface of both the main cleaning chamber ( 4 ) and the post-cleaning chamber ( 5 ) practically completely, the bottom ( 19 ) of the post-cleaning chamber ( 5 ) has a plurality of passage openings ( 26 ). 22. Exhaust gas purification device according to one of claims 12-21, characterized in that the sedimentation container ( 20 ) on the main cleaning chamber ( 4 ) and on the post-cleaning chamber ( 5 ) or on a housing ( 1 ) containing said chambers is releasably attached. 23. Exhaust gas purification device according to one of claims 12-22, characterized by a - seen in the flow direction of the exhaust gases - after the post-cleaning chamber ( 5 ) arranged catalyst chamber with an exhaust gas catalyst to reduce the exhaust gas pollutants. 24. An exhaust gas cleaning device according to claim 23, characterized by a fluidic separation between the post-cleaning chamber ( 5 ) and the catalyst chamber ( 6 ) which is effective for the cleaning liquid ( 11 ). 25. Exhaust gas purification device according to claim 24, characterized by a separation between the post-cleaning chamber ( 5 ) and the catalyst chamber ( 6 ) such that the catalyst chamber ( 6 ) above the maximum possible level in operation ( 10 ) of the cleaning liquid ( 11 ) is arranged is.