WO1986003552A1 - Gas purifying device - Google Patents

Gas purifying device Download PDF

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Publication number
WO1986003552A1
WO1986003552A1 PCT/DE1985/000300 DE8500300W WO8603552A1 WO 1986003552 A1 WO1986003552 A1 WO 1986003552A1 DE 8500300 W DE8500300 W DE 8500300W WO 8603552 A1 WO8603552 A1 WO 8603552A1
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WO
WIPO (PCT)
Prior art keywords
electrodes
housing
particles
coagulator
gas
Prior art date
Application number
PCT/DE1985/000300
Other languages
German (de)
French (fr)
Inventor
Ilan Brauer
Gerhard BRÜGGEN
Manfred Gaugler
Dieter Karr
Original Assignee
Robert Bosch Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO1986003552A1 publication Critical patent/WO1986003552A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/01—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust by means of electric or electrostatic separators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/017—Combinations of electrostatic separation with other processes, not otherwise provided for
    • B03C3/0175—Amassing particles by electric fields, e.g. agglomeration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/02—Plant or installations having external electricity supply
    • B03C3/04—Plant or installations having external electricity supply dry type
    • B03C3/09—Plant or installations having external electricity supply dry type characterised by presence of stationary flat electrodes arranged with their flat surfaces at right angles to the gas stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0892—Electric or magnetic treatment, e.g. dissociation of noxious components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to a device for cleaning gases according to the preamble of the main claim, as it has already become known from DE-OS 32 38 793.8.
  • the device described there is designed such that hollow cylindrical or flat electrodes are arranged in the flow direction of the gases to be cleaned. This means that a relatively large volume is required for the device in order to effect sufficient coagulation of the particles for the subsequent mechanical separation.
  • the device according to the invention with the characterizing features of the main claim has the advantage that due to the special field conditions and / or through longer distances there is a greater coagulation of the particles to be separated, so that a good efficiency can be achieved with a compact system.
  • An arrangement in which the electrodes are designed as wire grids and through which the gas to be cleaned flows has proven to be a particularly expedient design.
  • This arrangement has the advantage that there is approximately the same flow velocity of the gases in the area of the entire device, so that the structural design of the arrangement can be easily optimized.
  • the parallel arrangement of a plurality of such wire electrodes also results in a high electric field strength at a relatively low high voltage.
  • the wire material of the wire grids used for the electrodes should be dimensioned such that the grids can be designed to be self-supporting and require no additional mechanical stiffeners which increase the design effort.
  • the electrodes are designed as disk-shaped sheets, which deflect the gas flow and thereby considerably lengthen the path of the gases and increase the coagulation rate.
  • an arrangement has proven to be expedient in which the electrodes at high voltage potential are mounted on a common carrier, while the electrodes at ground potential are attached to a housing wall.
  • the number of bushings for the high voltage to be insulated from the housing is limited to one or possibly two places, which further simplifies the structural design of the device.
  • the ground electrodes fastened in the housing are provided with a slot for the carrier to pass through.
  • Another advantageous design of the two electrode groups can be designed in such a way that the high-voltage electrodes and the ground electrodes are each fastened to a disc end on a common carrier or to the housing wall, so that the electrode groups are pushed into one another when the device is assembled without a threading slot or the like can.
  • the electrodes and the housing surrounding them may be round, oval or rectangular.
  • a round arrangement has the advantage that the same flow conditions prevail at practically every location within the device, while an oval or rectangular configuration with a correspondingly predetermined installation space allows a larger volume of the device, which may increase the efficiency if necessary.
  • FIG. 1 shows a longitudinal section by a device according to the invention and Figure 2 is a plan view of an electrode made of a wire mesh.
  • arrows 10 indicate a gas flow which, when entering the device, is loaded with the finely divided particles to be separated via a nozzle 11.
  • the gas stream 10 leaves the part of the device according to the invention which is of interest here via a connecting piece 12 to a centrifugal separator 18, from which a cleaned gas stream 19a on the one hand and the separated particles 19b on the other hand emerge.
  • the high-voltage part of the device referred to below as the coagulator, has a housing 13 made of sheet metal, which in the exemplary embodiment shown is designed as a cylindrical jacket part and is connected to ground potential.
  • the end wall of the coagulator facing the gas inlet is designated by 14, the opposite end wall on the gas outlet side by 15.
  • An electrically conductive support 16 is held in an insulator 17 in the end wall 14.
  • the carrier is due to positive high voltage potential.
  • the opposite end of the carrier 16 can additionally be mounted on the end wall 15 by means of a holder 20 if the size of the device or particularly strong mechanical loads, for example in a motor vehicle, require this.
  • the end walls 14 and 15 of the coagulator are preferably made of electrically non-conductive material.
  • disc-shaped electrodes 21 which are at high voltage potential are electrically and mechanically fastened on the carrier 16.
  • Figure 2 shows the design of the high-voltage electrodes 21 from a wire mesh 25 which is braided from individual wires 26 and has a stiffening edge 27.
  • the electrodes 22, which are at ground potential, also consist of a corresponding wire mesh with a similar mesh and essentially the same dimensions.
  • the carrier 16 on which the high-voltage electrodes 21 are held can be seen in the middle of the wire grid 25.
  • the design according to the invention achieves a significant increase in efficiency.
  • the disk-shaped electrodes 21 and 22 are connected in parallel in large numbers and alternately acted upon with positive and negative potential in an arrangement that results in an electric field strength below the ionization field strength. In the case of corresponding systems, it has proven useful to limit the electric field strength to a value of approximately 10 kV / cm.
  • the distance between the electrodes 21 and 22 should be approximately 5 mm to 10 mm, on the one hand to achieve a high field strength and on the other hand to avoid contact between the electrodes with certainty.
  • the same flow rate and a large active electrode area are achieved in the entire coagulator area.
  • the latter causes particles with Store a sufficiently high dielectric constant in the electric field on the metallic electrodes 21 and 22 and grow together to form larger agglomerates if the flow velocity within the arrangement does not exceed a predetermined value of, for example, less than 1 m / s.
  • a dielectric constant of approx. 100 was measured for soot particles in the exhaust gas of diesel engines. If the particles, which become dipoles due to the electric field, are close to the charged electrode surface 21 or 22, they experience an acceleration towards the surface because they are attracted to the surface due to the opposite polarity of the dipoles.
  • Soot particles predominantly have rod-like geometries. They are therefore particularly easy to align in the electrical field and are therefore very suitable for the intended, temporary attachment process to the electrodes.
  • adhesive forces hold the particle at one end of the rod. There is some charge equalization because the carbon of the soot particles is semiconducting.
  • the free end of the individual attached particle or the free end of the attached agglomerate has the same charge as the electrode surface. The repulsive effect due to the electrical charges of the same name is canceled out by adhesive forces.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Toxicology (AREA)
  • Electrostatic Separation (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

Device for removing particles or droplets from gases particularly exhaust gases during the combustion of fosil fuels specially for diesel engines. The device includes a coagulator with high voltage elctrodes (21, 22) wherein the small particles are transformed in dipoles by polarization or by influence and form aglomerates of larger size. Thus, the efficiency of a mechanical separator (18) arranged after the gas travel line is enhanced. The electrodes (21, 22) are provided in a housing (13) of the coagulator perpendicular to the gas stream (10). Thereby the efficiency of the device, with respect to a given volume, is substantially improved.

Description

Vorrichtung zum Reinigen von GasenDevice for cleaning gases
Stand der TechnikState of the art
Die Erfindung geht aus von einer Vorrichtung zum Reinigen von Gasen nach der Gattung des Hauptanspruches, wie sie aus der DE-OS 32 38 793.8 bereits bekanntgeworden ist. Die dort beschriebene Vorrichtung ist so ausgebildet, daß hohlzylindrische oder ebene Elektroden in Strömungsrichtung der zu reinigenden Gasen angeordnet sind. Dies führt dazu, daß ein relativ großes Volumen für die Vorrichtung benötigt wird um eine ausreichende Koagulation der Partikel für die anschließende mechanische Abscheidung zu bewirken.The invention relates to a device for cleaning gases according to the preamble of the main claim, as it has already become known from DE-OS 32 38 793.8. The device described there is designed such that hollow cylindrical or flat electrodes are arranged in the flow direction of the gases to be cleaned. This means that a relatively large volume is required for the device in order to effect sufficient coagulation of the particles for the subsequent mechanical separation.
Weiterhin ist es aus der DE-OS 33 14 170 bekannt, innerhalb eines Koagulators eine Prallfläche im Gasstrom anzuordnen, welche auf Massepotential liegt und auf ihrer Oberfläche positiv geladene Partikel anlagert. Diese Partikel wachsen auf der Oberfläche zu größeren Agglomeraten zusammen, bevor sie durch die Gasströmung wieder abgelöst werden und zur mechanischen Abscheidung in einen nachgeschalteten Fliehkraftabscheider oder dgl. gelangen. Vorteile der ErfindungFurthermore, it is known from DE-OS 33 14 170 to arrange a baffle in the gas flow within a coagulator, which is at ground potential and has positively charged particles on its surface. These particles grow together on the surface to form larger agglomerates before they are detached again by the gas flow and reach a downstream centrifugal separator or the like for mechanical separation. Advantages of the invention
Die erfindungsgemäße Vorrichtung mit den kennzeichnenden Merkmalen des Hauptanspruches hat demgegenüber den Vorteil, daß aufgrund der besonderen Feldverhältnisse und/oder durch längere Wege eine stärkere Koagulation der abzuscheidenden Partikel erfolgt, so daß mit einer kompakten Anlage ein guter Wirkungsgrad erzielbar ist.The device according to the invention with the characterizing features of the main claim has the advantage that due to the special field conditions and / or through longer distances there is a greater coagulation of the particles to be separated, so that a good efficiency can be achieved with a compact system.
Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Hauptanspruch angegebenen Vorrichtung möglich. Als eine besonders zweckmäßige Bauform hat sich dabei eine Anordnung bewährt, bei der die Elektroden als Drahtgitter ausgebildet und von dem zu reinigenden Gas durchströmt sind. Diese Anordnung hat den Vorteil, daß im Bereich der gesamten Vorrichtung etwa die gleiche Strömungsgeschwindigkeit der Gase herrscht, so daß sich die bauliche Gestaltung der Anordnung leicht optimieren läßt. Durch die parallele Anordnung einer Mehrzahl derartiger Drahtelektroden erhält man überdies bei relativ niedriger Hochspannung eine hohe elektrische Feldstärke. Das Drahtmaterial der für die Elektroden verwendeten Drahtgitter sollte dabei so bemessen sein, daß die Gitter selbsttragend gestaltet werden können und keine zusätzlichen mechanischen Versteifungen benötigen, welche den konstruktiven Aufwand erhöhen.Advantageous further developments and improvements of the device specified in the main claim are possible through the measures listed in the subclaims. An arrangement in which the electrodes are designed as wire grids and through which the gas to be cleaned flows has proven to be a particularly expedient design. This arrangement has the advantage that there is approximately the same flow velocity of the gases in the area of the entire device, so that the structural design of the arrangement can be easily optimized. The parallel arrangement of a plurality of such wire electrodes also results in a high electric field strength at a relatively low high voltage. The wire material of the wire grids used for the electrodes should be dimensioned such that the grids can be designed to be self-supporting and require no additional mechanical stiffeners which increase the design effort.
Bei einer anderen vorteilhaften Ausgestaltung der Erfindung sind die Elektroden als scheibenförmige Bleche ausgebildet, welche den Gasstrom jeweils umlenken und hierdurch den Weg der Gase beträchtlich verlängern und die Koagulationsrate erhöhen. In beiden genannten Ausgestaltungen hat sich eine Anordnung als zweckmäßig erwiesen, bei der die auf Hochspannungspotential liegenden Elektroden auf einen gemeinsamen Träger montiert sind, während die auf Massepotential liegenden Elektroden an einer Gehäusewand befestigt sind. Hierdurch wird die Anzahl der gegenüber dem Gehäuse zu isolierenden Durchführungen für die Hochspannung auf eine oder gegebenenfalls zwei Stellen beschränkt, wodurch die bauliche Gestaltung der Vorrichtung weiter vereinfacht wird. Bei einer Vormontage der Hochspannungs-Elektroden auf einem gemeinsamen Träger werden die im Gehäuse befestigten Masse-Elektroden mit einem Schlitz für den Durchtritt des Träger versehen. Eine andere vorteilhafte Gestaltung der beiden Elektrodengruppen kann derart ausgebildet werden, daß die Hochspannungs-Elektroden und die Masseelektroden jeweils an einem Scheibenende auf einem gemeinsamen Träger oder an der Gehäusewand befestigt sind, so daß die Elektrodengruppen ohne Einfädelschlitz oder dgl. beim Zusammenbau der Vorrichtung ineinandergeschoben werden können.In another advantageous embodiment of the invention, the electrodes are designed as disk-shaped sheets, which deflect the gas flow and thereby considerably lengthen the path of the gases and increase the coagulation rate. In both of the configurations mentioned, an arrangement has proven to be expedient in which the electrodes at high voltage potential are mounted on a common carrier, while the electrodes at ground potential are attached to a housing wall. As a result, the number of bushings for the high voltage to be insulated from the housing is limited to one or possibly two places, which further simplifies the structural design of the device. When the high-voltage electrodes are preassembled on a common carrier, the ground electrodes fastened in the housing are provided with a slot for the carrier to pass through. Another advantageous design of the two electrode groups can be designed in such a way that the high-voltage electrodes and the ground electrodes are each fastened to a disc end on a common carrier or to the housing wall, so that the electrode groups are pushed into one another when the device is assembled without a threading slot or the like can.
Je nach der vorangigen Zielsetzung kann es zweckmäßig sein, die Elektroden und das sie umschließende Gehäuse rund, oval oder rechteckig auszubilden. Eine runde Anordnung hat den Vorteil, daß praktisch an jedem Ort innerhalb der Vorrichtung gleiche Strömungsverhältnisse herrschen, während eine ovale oder rechteckige Ausgestaltung bei einem entsprechend vorgegebenen Einbauraum ein größeres Volumen der Vorrichtung zuläßt, wodurch gegebenenfalls der Wirkungsgrad erhöht werden kann.Depending on the previous objective, it may be appropriate to design the electrodes and the housing surrounding them to be round, oval or rectangular. A round arrangement has the advantage that the same flow conditions prevail at practically every location within the device, while an oval or rectangular configuration with a correspondingly predetermined installation space allows a larger volume of the device, which may increase the efficiency if necessary.
Zeichnungdrawing
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 einen Längsschnitt durch eine erfindungsgemäße Vorrichtung und Figur 2 eine Draufsicht auf eine Elektrode aus einem Drahtgitter.An embodiment of the invention is shown in the drawing and explained in more detail in the following description. 1 shows a longitudinal section by a device according to the invention and Figure 2 is a plan view of an electrode made of a wire mesh.
Beschreibung des AusführungsbeispielesDescription of the embodiment
In Figur 1 ist durch Pfeile 10 ein Gasstrom angedeutet, welcher beim Eintritt in die Vorrichtung über einen Stutzen 11 mit den abzusondernden, feinverteilten Partikeln beladen ist. Der Gasstrom 10 verläßt den hier interessierenden Teil der erfindungsgemäßen Vorrichtung über einen Stutzen 12 zu einem Fliehkraftabscheider 18 hin, aus dem einerseits ein gereinigter Gasstrom 19a und andererseits die abgesonderten Partikel 19b austreten.In FIG. 1, arrows 10 indicate a gas flow which, when entering the device, is loaded with the finely divided particles to be separated via a nozzle 11. The gas stream 10 leaves the part of the device according to the invention which is of interest here via a connecting piece 12 to a centrifugal separator 18, from which a cleaned gas stream 19a on the one hand and the separated particles 19b on the other hand emerge.
Der im folgenden als Koagulator bezeichnete Hochspannungsteil der Vorrichtung besitzt ein Gehäuse 13 aus Blech, welches im gezeichneten Ausführungsbeispiel als zylindrisches Mantelteil ausgebildet und auf Massepotential gelegt ist. Die dem Gaseintritt zugewandte Stirnwand des Koagulators ist mit 14 bezeichnet, die gegenüberliegende Stirnwand auf der Gasaustrittsseite mit 15. In der Stirnwand 14 ist ein elektrisch leitfähiger Träger 16 in einem Isolator 17 gehalten. Der Träger liegt an positivem Hochspannungspotential. Das gegenüberliegende Ende des Trägers 16 kann zusätzlich mittels einer Halterung 20 an der Stirnwand 15 gelagert werden, wenn die Größe der Vorrichtung oder besonders starke mechanische Beanspruchungen, beispielsweise in einem Kraftfahrzeug, dies erfordern. Die Stirnwände 14 und 15 des Koagulators bestehen vorzugsweise aus elektrisch nichtleitendem Material.The high-voltage part of the device, referred to below as the coagulator, has a housing 13 made of sheet metal, which in the exemplary embodiment shown is designed as a cylindrical jacket part and is connected to ground potential. The end wall of the coagulator facing the gas inlet is designated by 14, the opposite end wall on the gas outlet side by 15. An electrically conductive support 16 is held in an insulator 17 in the end wall 14. The carrier is due to positive high voltage potential. The opposite end of the carrier 16 can additionally be mounted on the end wall 15 by means of a holder 20 if the size of the device or particularly strong mechanical loads, for example in a motor vehicle, require this. The end walls 14 and 15 of the coagulator are preferably made of electrically non-conductive material.
Innerhalb des Gehäuses 13 sind scheibenförmig ausgebildete, auf Hochspannungspotential liegende Elektroden 21 auf dem Träger 16 elektrisch und mechanisch befestigt. Die jeweils zwischen zwei Hochspannungselektroden 21 angeordneten, auf Massepotential liegenden Elektroden 22 sind beim gezeichneten Ausführungsbeispiel einzeln am geerdeten Gehäuse 13 befestigt.Within the housing 13, disc-shaped electrodes 21 which are at high voltage potential are electrically and mechanically fastened on the carrier 16. The electrodes 22, which are arranged between two high-voltage electrodes 21 and are at ground potential, are individually attached to the grounded housing 13 in the illustrated embodiment.
Figur 2 zeigt die Gestaltung der Hochspannungs-Elektroden 21 aus einem Drahtgitter 25, welches aus einzelnen Drähten 26 geflochten ist und einen Versteifungsrand 27 besitzt. Auch die auf Massepotential liegenden Elektroden 22 bestehen aus einem entsprechenden Drahtgitter mit gleichartigem Geflecht und im wesentlichen gleichen Abmessungen. In der Mitte des Drahtgitters 25 ist der Träger 16 zu erkennen, auf dem die Hochspannungselektroden 21 gehalten sind.Figure 2 shows the design of the high-voltage electrodes 21 from a wire mesh 25 which is braided from individual wires 26 and has a stiffening edge 27. The electrodes 22, which are at ground potential, also consist of a corresponding wire mesh with a similar mesh and essentially the same dimensions. The carrier 16 on which the high-voltage electrodes 21 are held can be seen in the middle of the wire grid 25.
Gegenüber einer bekannten Koagulator-Vorrichtung mit gleichem Bauvolumen und hohlzylindrischer Anordnung der Elektroden erreicht man durch die erfindungsgemäße Bauform eine wesentliche Steigerung des Wirkungsgrades. Die scheibenförmigen Elektroden 21 und 22 sind dabei in großer Anzahl parallel geschaltet und alternierend mit positivem und negativem Potential beaufschlagt in einer Anordnung, daß sich eine elektrische Feldstärke unterhalb der Ionisationsfeldstärke ergibt. Bei entsprechenden Anlagen hat es sich bewährt, die elektrische Feldstärke auf einen Wert von ca. 10 kV/cm zu begrenzen. Der Abstand der Elektroden 21 und 22 untereinander sollte ca. 5 mm bis 10 mm betragen, um einerseits eine hohe Feldstärke zu erzielen und andererseits Berührungen zwischen den Elektroden mit Sicherheit zu vermeiden. Bei beiden Bauformen der erfindungsgemäßen Vorrichtung erreicht man im gesamten Koagulatorbereich eine gleiche Strömungsgeschwindigkeit und eine große aktive Elektrodenfläche. Letztere bewirkt, daß sich Partikel mit ausreichend hoher Dielektrizitätszahl im elektrischen Feld an den metallischen Elektroden 21 und 22 vorübergehend ablagern und zu größeren Agglomeraten zusammenwachsen, wenn die Strömungsgeschwindigkeit innerhalb der Anordnung einen vorgegebenen Wert von beispielsweise kleiner 1 m/s nicht überschreitet. Bei Rußpartikeln im Abgas von Dieselmotoren wurde eine Dielektrizitätszahl von ca. 100 gemessen. Befinden sich die Partikel, welche aufgrund des elektrischen Feldes zu Dipolen werden, dicht vor der geladenen Elektrodenoberfläche 21 oder 22, so erfahren sie eine Beschleunigung zur Oberfläche hin, weil sie aufgrund der gegenpoligen Ausrichtung der Dipole von der Oberfläche angezogen werden.Compared to a known coagulator device with the same overall volume and a hollow cylindrical arrangement of the electrodes, the design according to the invention achieves a significant increase in efficiency. The disk-shaped electrodes 21 and 22 are connected in parallel in large numbers and alternately acted upon with positive and negative potential in an arrangement that results in an electric field strength below the ionization field strength. In the case of corresponding systems, it has proven useful to limit the electric field strength to a value of approximately 10 kV / cm. The distance between the electrodes 21 and 22 should be approximately 5 mm to 10 mm, on the one hand to achieve a high field strength and on the other hand to avoid contact between the electrodes with certainty. With both designs of the device according to the invention, the same flow rate and a large active electrode area are achieved in the entire coagulator area. The latter causes particles with Store a sufficiently high dielectric constant in the electric field on the metallic electrodes 21 and 22 and grow together to form larger agglomerates if the flow velocity within the arrangement does not exceed a predetermined value of, for example, less than 1 m / s. A dielectric constant of approx. 100 was measured for soot particles in the exhaust gas of diesel engines. If the particles, which become dipoles due to the electric field, are close to the charged electrode surface 21 or 22, they experience an acceleration towards the surface because they are attracted to the surface due to the opposite polarity of the dipoles.
Rußpartikel besitzen überwiegend stäbchenförmige Geometrien. Sie richten sich deshalb im elektrischen Feld besonders leicht aus und eignen sich daher sehr gut für den vorgesehenen, zeitlich begrenzten Anlagerungsprozess an den Elektroden. Beim Auftreffen eines Dipol-Teilchen auf einer Elektrodenoberfläche halten Adhäsionskräfte das Teilchen an einem Stabende fest. Es findet teilweise ein Ladungsausgleich statt, da der Kohlenstoff der Rußpartikel halbleitend ist. Das freie Ende des einzelnen angelagerten Partikels, bzw. das freie Ende des angelagerten Agglomerates besitzt die gleiche Ladung wie die Elektrodenoberfläche. Die abstoßende Wirkung aufgrund der gleichnamigen elektrischen Ladungen wird durch Adhäsionskräfte aufgehoben.Soot particles predominantly have rod-like geometries. They are therefore particularly easy to align in the electrical field and are therefore very suitable for the intended, temporary attachment process to the electrodes. When a dipole particle hits an electrode surface, adhesive forces hold the particle at one end of the rod. There is some charge equalization because the carbon of the soot particles is semiconducting. The free end of the individual attached particle or the free end of the attached agglomerate has the same charge as the electrode surface. The repulsive effect due to the electrical charges of the same name is canceled out by adhesive forces.
Am freien Ende des angelagerten Partikels oder Agglomerates entsteht ein sehr starkes inhomogenes Feld wegen der hohen anliegenden Spannung und des kleinen Krümmungsradius der Partikel, beispielsweise eines Krümmungsradius von 40 nm bei stäbchenförmigen Rußpartikel. In diesem stark inhomogenen elektrischen Feld werden nun die benachbarten Dipole zum Ort der größten Feldstärke beschleunigt, weshalb sich die nächsten Partikel am freien Ende des auf der Elektrode sitzenden Partikels anlagern. Dieser Mechanismus führt zum raschen Anwachsen eines turmartigen Gebildes auf der elektrisch leitfähigen Elektrode. Der Wachstumsprozeß endet, wenn die Ablösekräfte der strömenden Gase auf das Agglomerat größer als die adhäsiven Kräfte zwischen der Elektrode und dem Agglomerat werden. Letzteres wird weggespült und ein neuer Anlagerungsprozeß kann beginnen. Dieser Koagulationsmechanismus findet unabhängig und zusätzlich zu dem innerhalb des Gasstromes stattfindenden Anlagerungsprozeß aufgrund der Dipolladungen der Partikel untereinander statt. Der Wirkungsgrad der Anlage wird dadurch sehr hoch und man erzielt auf kleinem Raum eine hohe Koagulationsrate und damit eine wirkungsvolle Abscheidung im nachgeschalteten mechanischen Abscheider 18. At the free end of the attached particle or agglomerate, a very strong inhomogeneous field arises because of the high applied voltage and the small radius of curvature of the particles, for example a radius of curvature of 40 nm in the case of rod-shaped soot particles. In this highly inhomogeneous electric field now accelerates the neighboring dipoles to the location of the greatest field strength, which is why the next particles accumulate at the free end of the particle sitting on the electrode. This mechanism leads to the rapid growth of a tower-like structure on the electrically conductive electrode. The growth process ends when the stripping forces of the flowing gases on the agglomerate become greater than the adhesive forces between the electrode and the agglomerate. The latter is washed away and a new attachment process can begin. This coagulation mechanism takes place independently and in addition to the accumulation process taking place within the gas flow due to the dipole charges of the particles among one another. As a result, the efficiency of the system becomes very high and a high coagulation rate and thus an effective separation in the downstream mechanical separator 18 are achieved in a small space.

Claims

Ansprüche Expectations
1. Vorrichtung zum Reinigen von Gasen von Teilchen oder Tröpfchen , insbe sondere zum Reinigen von Abgasen fossiler Brennstoffe, vorzugsweise von Dieselmotoren, mit einem mechanischen Abscheider und einem diesem vorgeschalteten Koagulator mit ebenen Elektroden, welche vorzugsweise mit alternierender Polarität parallel zueinander angeordnet und elektrisch parallel geschaltet sind, wobei an den Elektroden ein elektrisches Hochspannungsfeld liegt, insbesondere ein stationäres Hochspannungsfeld, mit einer Feldstärke unterhalb der Ionisationsfeldstärke, durch dessen Einwirkung die Partikel zu größeren Agglomeraten koagulieren, dadurch gekennzeichnet, daß die Elektroden (21, 22) im wesentlichen senkrecht zum Gasstrom (10) angeordnet sind.1. Device for cleaning gases from particles or droplets, in particular for cleaning exhaust gases from fossil fuels, preferably from diesel engines, with a mechanical separator and an upstream coagulator with flat electrodes, which are preferably arranged in parallel with one another with alternating polarity and electrically connected in parallel whereby an electrical high-voltage field is present on the electrodes, in particular a stationary high-voltage field with a field strength below the ionization field strength, by the action of which the particles coagulate to form larger agglomerates, characterized in that the electrodes (21, 22) are essentially perpendicular to the gas flow ( 10) are arranged.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die Elektroden (21, 22) verschiedener Polarität einen gegenseitigen Abstand von 2 mm bis 20 mm, vorzugsweise von 5 mm bis 10 mm haben.2. Device according to claim 1, characterized in that the electrodes (21, 22) of different polarity have a mutual distance of 2 mm to 20 mm, preferably from 5 mm to 10 mm.
3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Elektroden (21, 22) als Drahtgitter ausgebildet und von dem zu reinigenden Gas (10) durchströmt sind. 3. Apparatus according to claim 1 or 2, characterized in that the electrodes (21, 22) are designed as a wire mesh and are flowed through by the gas to be cleaned (10).
4. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, daß das Elektroden-Draht gitter (25) selbsttragend ausgebildet ist.4. The device according to claim 3, characterized in that the electrode wire grid (25) is self-supporting.
5. Vorrichtung nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß das Drahtgitter (25) aus Drähten (26) mit einem Durchmesser von 0,3 mm bis 1 mm hergestellt ist.5. Apparatus according to claim 3 or 4, characterized in that the wire mesh (25) made of wires (26) with a diameter of 0.3 mm to 1 mm.
6. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Elektroden (21, 22) aus Blechen bestehen, an denen der Gasstrom umgelenkt wird.6. The device according to claim 1 or 2, characterized in that the electrodes (21, 22) consist of sheets on which the gas flow is deflected.
7. Vorrichtung nach einem der vorhergehenden Ansprüchen, dadurch gekennzeichnet, daß die Elektroden (21) mit Hochspannungspoteήtial auf einem gemeinsamen, gegenüber einem auf Massepotential liegenden Gehäuse (13) isolierten Träger (16) sitzen, während die Elektroden (22) mit Massepotential einzeln oder gemeinsam an einer Gehäusewand (13) befestigt sind.7. Device according to one of the preceding claims, characterized in that the electrodes (21) with high voltage potential sit on a common carrier (16) insulated from a housing (13) which is at ground potential, while the electrodes (22) individually or at ground potential are fixed together on a housing wall (13).
8. Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Elektroden (21, 22) und das sie umschließende Gehäuse (13) kreisförmig oder oval ausgebildet sind.8. Device according to one of the preceding claims, characterized in that the electrodes (21, 22) and the housing (13) surrounding them are circular or oval.
9. Vorrichtung nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß die Elektroden (21, 22) und das sie umschließende Gehäuse (13) rechteckig ausgebildet sind. 9. Device according to one of claims 1 to 7, characterized in that the electrodes (21, 22) and the housing (13) surrounding them are rectangular.
PCT/DE1985/000300 1984-12-13 1985-08-31 Gas purifying device WO1986003552A1 (en)

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DE19843445406 DE3445406A1 (en) 1984-12-13 1984-12-13 DEVICE FOR CLEANING GASES
DEP3445406.3 1984-12-13

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DE9407861U1 (en) * 1994-05-11 1995-10-19 Siemens AG, 80333 München Device for the detoxification of exhaust gases from mobile systems
CN113356966B (en) * 2021-06-17 2023-05-26 东风小康汽车有限公司重庆分公司 Automobile exhaust particle processor and exhaust treatment device

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FR834510A (en) * 1937-07-27 1938-11-23 Device for suppressing exhaust fumes from automobiles, locomotives and other similar devices
JPS57186012A (en) * 1981-05-13 1982-11-16 Fuji Electric Corp Res & Dev Ltd Exhaust gas purifier for internal combustion engine
DE3141156A1 (en) * 1981-10-16 1983-04-28 Robert Bosch Gmbh, 7000 Stuttgart METHOD AND DEVICE FOR REMOVING SOLID COMPONENTS AND AEROSOLS, ESPECIALLY SOOT COMPONENTS FROM THE EXHAUST GAS FROM COMBUSTION ENGINES
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Publication number Priority date Publication date Assignee Title
DE322188C (en) * 1918-12-05 1920-06-22 Siemens Schuckertwerke G M B H Electrical system for cleaning gases
FR834510A (en) * 1937-07-27 1938-11-23 Device for suppressing exhaust fumes from automobiles, locomotives and other similar devices
JPS57186012A (en) * 1981-05-13 1982-11-16 Fuji Electric Corp Res & Dev Ltd Exhaust gas purifier for internal combustion engine
DE3141156A1 (en) * 1981-10-16 1983-04-28 Robert Bosch Gmbh, 7000 Stuttgart METHOD AND DEVICE FOR REMOVING SOLID COMPONENTS AND AEROSOLS, ESPECIALLY SOOT COMPONENTS FROM THE EXHAUST GAS FROM COMBUSTION ENGINES
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