WO1997040265A1 - Procede et dispositif de traitement d'un effluent gazeux - Google Patents

Procede et dispositif de traitement d'un effluent gazeux Download PDF

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Publication number
WO1997040265A1
WO1997040265A1 PCT/EP1997/002070 EP9702070W WO9740265A1 WO 1997040265 A1 WO1997040265 A1 WO 1997040265A1 EP 9702070 W EP9702070 W EP 9702070W WO 9740265 A1 WO9740265 A1 WO 9740265A1
Authority
WO
WIPO (PCT)
Prior art keywords
discharge
electrodes
electrode
reactor
exhaust gas
Prior art date
Application number
PCT/EP1997/002070
Other languages
German (de)
English (en)
Inventor
Klaus Pochner
Willi Neff
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Publication of WO1997040265A1 publication Critical patent/WO1997040265A1/fr

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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
    • F01N3/08—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/32—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00
    • B01D53/323—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00 by electrostatic effects or by high-voltage electric fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/818—Employing electrical discharges or the generation of a plasma

Definitions

  • the invention relates to a method for treating exhaust gas according to the preamble of claim 1 and a device for treating exhaust gas, in particular for carrying out the method according to the preamble of claim 1 1.
  • the invention is used in all areas of technology in which flowing Exhaust gases to reduce pollutants have to be subjected to post-treatment, for example in automotive technology, in power plants or waste incineration plants.
  • Incoherent plasma radiation sources "; Ratio DPG (VI 31 (1996) 701, M. Neiger.” Incoherent plasma radiation sources, “lecture. , DPG spring conference Plasma physics, Rostock, March 21, 1996.). Further positive effects are expected from the interaction of molecules or radicals from the discharge with water or oil mist (cluster) and with particles in the exhaust gas (A. Czernichowski in: Workshop on Plasma Based Environmental Technologies; Berlin, December 7th) 1995.). Due to the flow profile and temperature profile as well as diffusion, however, a smaller concentration of these reactive centers is rather present in the narrow, particularly reactive area.
  • the type of discharge used for a corona discharge with a sharp-edged inner electrode, long distances and a pulsed power supply is significantly less efficient than the barrier discharge proposed here because of the strongly inhomogeneous electric field and the switching losses in the supply device.
  • DeNOx catalysts for the selective reduction of nitrogen oxides in oxygen-containing exhaust gas are also under development (G. Lepperhoff: “NOx reduction in DeNOx catalysts due to hydrocarbons in the exhaust gas from gasoline engines” in: Technische Aka ⁇ demie; Esslingen, 8. / December 9, 1994.), in which the addition of a chemical reducing agent to the exhaust gas is required in order to achieve good degrees of conversion.
  • Ammonia, urea or fuel, ie unburned hydrocarbons are proposed as reducing agents.
  • these additives could also be used in combination with barrier discharges to increase efficiency.
  • the expense of maintaining an exact dosage and the possible drastic increase in emissions in the case of imprecise regulation in transient operation are disadvantageous.
  • a device for plasma chemical conversion in which specific configurations for cooling the discharge medium are used, can be found in WO 94/23185 A1.
  • the temperature range of the equivalent of 65-150 ° C appears to be in a thermodynamically sensible, but hardly maintainable (full load!) Range.
  • the arc discharge as a thermal gas discharge heats electrons, ions and neutral particles equally to several thousand degrees, which already makes the proposed good heat dissipation through the wall necessary to prevent premature thermal destruction of the reactor.
  • a possible improvement in efficiency due to the lower operating temperature becomes an academic question in view of the wasted energy expenditure for heating the gas.
  • the specific setting of transverse temperature gradients in the discharge area is not apparent from the application.
  • the invention is based on the object of specifying a method and a device for the aftertreatment of exhaust gas with which the pollutant conversion is improved and the energy efficiency is increased.
  • a solution for the method with which the exhaust gas is to be treated is specified with the features of patent claim 1.
  • Advantageous further developments are specified in subclaims 2 to 10.
  • a solution for the device for treating exhaust gas is specified with the features of patent claim 11.
  • Advantageous refinements of the device according to the invention are specified in subclaims 12 to 23.
  • the discharge vessel hereinafter called the reactor, consists of a narrow gap in which the discharge is ignited and two flat electrodes which delimit the gap.
  • the gap can be closed off at the side, or the electrodes are rolled up to form a coaxial vessel. It is important that at least one of the electrodes on the side facing the discharge gas is covered by a dielectric barrier which gives the discharge its name. Every time a high-frequency high voltage rises, an electric field is created in the discharge space, which leads to the formation of streamer discharges. Due to the statistical nature of the ignition process, the discharge does not start at all points at the same time. The charge flowing through the streamer channels cannot flow to the electrodes via the insulating dielectric, and a surface charge builds up there, which shields the field applied from the outside in an environment around the streamer.
  • the discharge consists of a mosaic of small channels. If the distance between the voltage half-waves is sufficient, the channels in the next half-wave ignite again statistically distributed over the surface and the discharge appears homogeneous on average over time.
  • the coaxial reactor described here is only an example of further possible configurations, where plate stacks or tube bundles, among other things, are used in the same way.
  • the invention relates to all thermal or flow mechanical measures by means of which higher concentrations of certain substances are achieved in individual areas of the plasma reactor. Without increasing the raw concentration of these substances in the exhaust gas by changing the engine setting or by subsequent injection, a reductive area in otherwise oxidative exhaust gas can nevertheless be created locally, for example.
  • Fig. 1 Principle of dielectric discharge (barrier discharge)
  • Fig. 2 first embodiment of the device according to the invention
  • Fig. 3a Velocity profile of a laminar flow
  • Fig. 3d Profile of the maximum electric field strength
  • Fig. 4a coaxial reactor according to the prior art in cross section and in
  • Fig. 4b Coaxial electrode arrangement with a cooled outer electrode in
  • Fig. 4c Coaxial electrode arrangement with a cooled inner electrode in
  • Fig. 4d Coaxial electrode arrangement with cooling fins on the outer electrode in cross section and in Fig. 5b in perspective
  • Fig. 4e System of several parallel reactors in a common
  • the reactor consists of a high-voltage electrode 10 and a ground electrode 30, at least one of which is electrically isolated from the gas space by a dielectric 20.
  • the high-voltage electrode 10 is connected to an AC voltage source 50, not shown here; the gas to be treated flows through the gas space parallel to the electrodes (61, 62).
  • a gas discharge occurs which is formed at atmospheric pressure in the form of individual, homogeneously distributed filaments 71. These are spaced from each other by about the radius of their base 72 and are statistically generated on the entire electrode surface.
  • FIG. 2 shows a first embodiment of the device according to the invention.
  • a further wall 21 is applied tightly connected to the dielectric 20.
  • the intermediate space 12 is filled with a cooling liquid, for example water, which is contacted via an electrode 11. Because of the conductivity of undistilled water and the high dielectric constant, it is sufficient if the electrode 11 lies loosely on the dielectric 20.
  • the electrode 1 1 may have interruptions in the centimeter range without the homogeneity of the discharge 70 being disturbed.
  • a wire mesh or (for round electrodes) a wire spiral meet these requirements.
  • the disturbing corona discharges 79 which occur in air in the case of high-voltage electrodes are prevented by the housing 21.
  • the water filling 12 in the electrode can be replaced by means of lines (not shown here) and, if necessary, returned via heat exchangers.
  • FIGS. 3a and 3b speed profiles for a laminar (FIG. 3a) and turbulent (FIG. 3b) flow between two plates (19, 39) are shown. It is noteworthy that the slightest gas exchange takes place at the edge.
  • the turbulent flow has an approximately rectangular profile with an edge layer 65 which is exaggeratedly large here.
  • the importance of the edge area is further emphasized by a temperature profile (FIG. 3c) of a reactor cooled on one side but heated homogeneously in volume 60 and by a profile of the maximum electric field strength (FIG. 3d). This reaches its maximum in a range of approximately 100 ⁇ m in front of the dielectric 20.
  • FIGS. 4a-4e cross section and 5a-5e (perspective) describe examples of reactors in coaxial geometry.
  • a reactor according to the prior art (FIGS. 4a, 5a) is shown in section, wherein the ground electrode 30 can be used as shown as the outermost or as the innermost tube. Nonetheless, the dielectric 20 does not necessarily have to be attached on the inside and on the ground electrode.
  • a filamented gas discharge 70 is again generated in the gap, which for simplification is not shown here and in the following drawings.
  • the cooling of an electrode according to the invention by means of a water jacket can take place on the outside (FIGS. 4b, 5b) or on the inside (FIGS. 4c, 5c) or by a combination of both designs.
  • passive cooling devices such as, for example, ribs 31, can also be used on the outer ground electrode (FIGS. 4d, 5d). Modifications for the internal electrode and / or the high-voltage electrode, for example a heat pipe, were nevertheless tested. If several reactors 69 connected in parallel are required for greater gas throughput, they can also use a common water jacket 32 in an outer housing 35 (FIGS. 4e, 5e). Reference list
  • a dielectric barrier gas discharge barrier discharge
  • Device for the treatment of exhaust gas in particular for performing the method according to one of claims 1 to 10, with at least one pair of flat electrodes which are arranged opposite one another so that they form a discharge space between them, which is connected to a voltage source are so that an electric field is generated in the discharge space, with at least one electrode on each pair of electrodes the side facing the discharge space is coated with a dielectric, and wherein the exhaust gas flows through the discharge space, characterized in that means (12, 31, 32) for cooling are provided for one or more electrodes (10, 1 1, 30) .
  • a cooling liquid for example water (12, 32) is provided for cooling, with which the electrodes (10, 1 1, 30) are acted upon.
  • Electrodes are designed as plane-parallel plate electrodes or as a stack of a plurality of plate electrodes arranged one above the other.
  • the electrode pairs (10, 30) consist of a plate-shaped first electrode (30) and an opposite plate-shaped dielectric (20) that an electrically conductive structure as the second electrode ( 1 1) on the side of the dielectric (20) facing away from the discharge space, it is provided that this structure (1 1) is covered with a housing (21) and that the housing (21) is filled with coolant (12).
  • pairs of electrodes consist of an inner tubular electrode (10) and an outer tubular electrode (30) arranged coaxially therewith.
  • Device according to one of claims 17 to 20 characterized in that the outer electrode (30) is provided with cooling fins (31).
  • 22 Device according to one of claims 17 to 21, characterized in that a plurality of electrode pairs (10, 30) are arranged parallel to one another in a common, preferably cylindrical, housing (35) and that the housing (35) with the cooling element liquid (32) is filled.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Combustion & Propulsion (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Treating Waste Gases (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

L'invention concerne un procédé de traitement d'un effluent gazeux au moyen d'une décharge gazeuse bloquée dialectiquement (décharge d'arrêt), se consumant transversalement entre des électrodes planes formant un réacteur, entre lesquelles l'effluent gazeux à traiter s'écoule longitudinalement. L'invention est caractérisée en ce que dans les zones spatiales individuelles du réacteur, il se produit une concentration en composants provenant de l'effluent gazeux, plus élevée que dans le reste du réacteur. Un dispositif pour la mise en oeuvre de ce procédé comprend au moins une paire d'électrodes planes (11, 30) disposées l'une en face de l'autre, de manière à former un espace de décharge (70) entre elles. Les électrodes sont connectées à une source de tension (50), de manière à produire un champ électrique dans l'espace de décharge. En outre, pour chaque pair d'électrodes, au moins une électrode est garnie d'un diélectrique (20) sur le côté opposé à l'espace de décharge. L'espace de décharge est traversé par l'effluent gazeux à traiter. Le dispositif est caractérisé en ce qu'il comprend des moyens (12) pour le refroidissement d'une ou plusieurs électrodes.
PCT/EP1997/002070 1996-04-23 1997-04-23 Procede et dispositif de traitement d'un effluent gazeux WO1997040265A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1996116197 DE19616197C2 (de) 1996-04-23 1996-04-23 Verfahren zur Behandlung von Abgas
DE19616197.5 1996-04-23

Publications (1)

Publication Number Publication Date
WO1997040265A1 true WO1997040265A1 (fr) 1997-10-30

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WO (1) WO1997040265A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6461409B1 (en) * 1999-03-25 2002-10-08 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Device and method for treating flowing gases, in particular exhaust gases
US6660068B1 (en) * 1999-07-12 2003-12-09 Perkins Engines Company Limited Autoselective regenerating particulate filter
US7354558B2 (en) 2003-09-24 2008-04-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040052028A1 (en) * 2000-10-26 2004-03-18 O'reilly Fergal Atmospheric pressure plasma assembly
DE10337901A1 (de) * 2003-08-18 2005-03-24 Audi Ag Verfahren und Vorrichtung zur Synthese von Ammoniak und Verfahren zur Reinigung von Abgasen einer Brennkraftmaschine
DE102007047356A1 (de) * 2007-10-02 2009-04-09 Langner, Manfred H. Verfahren und Vorrichtung zum Reinigen eines heißen Luftstroms

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5768153A (en) * 1980-10-16 1982-04-26 Ube Ind Ltd Electric precipitation method
EP0158823A2 (fr) * 1984-04-14 1985-10-23 BROWN, BOVERI & CIE Aktiengesellschaft Procédé et dispositif pour la purification de gaz d'échappement
JPS62296521A (ja) * 1986-06-17 1987-12-23 Anelva Corp プラズマ処理装置
EP0659465A2 (fr) * 1993-12-23 1995-06-28 Fraunhofer-Gesellschaft Zur Förderung Der Angewandten Forschung E.V. Procédé et dispositif pour la purification de gaz d'échappement
JPH08206490A (ja) * 1995-02-01 1996-08-13 Nissin Electric Co Ltd ガス処理装置

Family Cites Families (2)

* Cited by examiner, † Cited by third party
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US5041145A (en) * 1990-05-15 1991-08-20 Niles Parts Co., Ltd. Bridged stream corona generator
US5419123A (en) * 1993-03-29 1995-05-30 Unlimited Technologies, Inc. Emission control device and method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5768153A (en) * 1980-10-16 1982-04-26 Ube Ind Ltd Electric precipitation method
EP0158823A2 (fr) * 1984-04-14 1985-10-23 BROWN, BOVERI & CIE Aktiengesellschaft Procédé et dispositif pour la purification de gaz d'échappement
JPS62296521A (ja) * 1986-06-17 1987-12-23 Anelva Corp プラズマ処理装置
EP0659465A2 (fr) * 1993-12-23 1995-06-28 Fraunhofer-Gesellschaft Zur Förderung Der Angewandten Forschung E.V. Procédé et dispositif pour la purification de gaz d'échappement
JPH08206490A (ja) * 1995-02-01 1996-08-13 Nissin Electric Co Ltd ガス処理装置

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 006, no. 149 (C - 118) 10 August 1982 (1982-08-10) *
PATENT ABSTRACTS OF JAPAN vol. 096, no. 012 26 December 1996 (1996-12-26) *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 193 (E - 617) 4 June 1988 (1988-06-04) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6461409B1 (en) * 1999-03-25 2002-10-08 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Device and method for treating flowing gases, in particular exhaust gases
US6660068B1 (en) * 1999-07-12 2003-12-09 Perkins Engines Company Limited Autoselective regenerating particulate filter
US7144448B2 (en) 1999-07-12 2006-12-05 Perkins Engines Company Limited Autoselective regenerating particulate filter
US7354558B2 (en) 2003-09-24 2008-04-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification system
DE102004044731B4 (de) * 2003-09-24 2013-10-02 Toyota Jidosha Kabushiki Kaisha Abgasreinigungssystem

Also Published As

Publication number Publication date
DE19616197C2 (de) 1998-04-09
DE19616197A1 (de) 1997-11-06

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