WO1995006225A1 - Ameliorations de l'elimination de gaz nocifs dans des emissions - Google Patents

Ameliorations de l'elimination de gaz nocifs dans des emissions Download PDF

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Publication number
WO1995006225A1
WO1995006225A1 PCT/GB1994/001818 GB9401818W WO9506225A1 WO 1995006225 A1 WO1995006225 A1 WO 1995006225A1 GB 9401818 W GB9401818 W GB 9401818W WO 9506225 A1 WO9506225 A1 WO 9506225A1
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WO
WIPO (PCT)
Prior art keywords
electrodes
electrode
auxiliary electrode
discharge
voltage
Prior art date
Application number
PCT/GB1994/001818
Other languages
English (en)
Inventor
John Ernest Harry
Original Assignee
British Technology Group Limited
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 British Technology Group Limited filed Critical British Technology Group Limited
Publication of WO1995006225A1 publication Critical patent/WO1995006225A1/fr

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Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
    • F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
    • F23G7/061—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating
    • F23G7/063—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating electric heating
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • This invention relates to improvements in removal of noxious gases and more particularly, but not exclusively, to improvements in apparatus for the oxidation of Volatile Organic Compounds (VOCs).
  • VOCs Volatile Organic Compounds
  • Advantages obtainable by using electric discharges for oxidising VOCs include: higher temperature and energy densities than combustion processes, alternative chemical routes; and greater conversion efficiencies where selective chemical transitions can be carried out.
  • Electric discharges can be used for the synthesis or destruction of chemical compounds in many ways using the different energy transition processes involved in the release of the potential energy over their different ranges of operation.
  • the incinerator comprises two electrodes which were effectively knife-blades, the distance between whose tapered edges varied smoothly. A potential difference was established across the electrodes and a region of an igniting portion of gas progressed in a longitudinal direction, between the electrodes.
  • apparatus for producing an electric arc comprising a first and a second electrode and means for establishing a potential difference across the two electrodes; a third or auxiliary electrode; means for applying a potential difference between the third or auxiliary electrode and at least one of the first and second electrodes such that the voltage required to achieve breakdown across the first and second electrodes is reduced.
  • the breakdown voltage is reduced by at least one half of its previous value.
  • the apparatus is fitted into an inceinerator and burns noxious products such as vocs.
  • the third, or auxiliary, electrode is positioned such that it is offset between the first and second electrodes. That is it is closer to the first electrode than to the second electrode.
  • the first and second electrodes have a larger surface area than the third electrode and they are dimensioned and arranged such that gas flows between a volume whose envelope is partially determined by the slope of the surface of each electrode.
  • the first and second electrodes may have surfaces which are curved in one or more planes, such that they form sloped portions of arcuate bounded laminae or portions of spherical or ovaloid bodies.
  • the electrodes are of relatively simple shapes which may be readily punched or stamped from metal sheets. This ensures the electrodes are cheap.
  • an auxiliary electrode adapted for insertion into an incinerator which is equipped with a first and second electrode, the auxiliary electrode having a power supply and being dimensioned and arranged with respect to the first and second electrodes such that voltage required across the first and second electrodes to achieve breakdown is reduced.
  • the arrangement in accordance with the second aspect may be retro fitted to existing equipment.
  • two or more auxiliary electrodes may be fitted.
  • the positioning of the third, fourth or higher order, auxiliary electrode is not crucial, but it should be such as to assist breakdown between the main electrodes to occur.
  • the establishment of a discharge emission site greatly increases effectiveness of operation and enables a lower breakdown voltage between the electrodes.
  • a low current of approximately 0.1 A supplies the third electrode.
  • Current is derived from an independent supply from that used to supply the primary electrodes.
  • suitable transforming may be provided such that a single electrical supply may be used.
  • a fullwave bridge rectifier may be used to supply the third, or auxiliary electrode.
  • a fourth, auxiliary, electrode may be connected to opposite arms of the bridge rectifier such that odd numbered half cycles are applied to the third electrode and even numbered half cycles are applied to the fourth electrode (or vice versa).
  • the power consumption of the auxiliary electrode driver circuit is less than IkW and preferably less than 500W. The saving this auxiliary circuit makes on the overall reactive power consumption of the device is considerable despite the slight increase in running costs due to increased frequency of electrode replacement.
  • the first and second electrodes are so dimensioned and arranged as to permit an igniting arc to move across their respective surfaces from a region of narrow gap to a wider gap. This movement is due partially to convection effects and partially to the movement of gas through the narrow region of what may be envisaged as a tapered necked region to a wider region.
  • the term used to described this phenomenon is called "Glydarc".
  • VOC incineration process depends on its inherent simplicity which requires the use of alternating current and therefore repeated ignition of the discharge to prevent a static discharge forming which would result in erosion of the electrodes.
  • a direct current to supply the arrangement.
  • the voltage breaks down the minimum gap between the electrodes on each half cycle of the supply voltage to form a short low voltage arc.
  • the arc then lengthens and reaches a discharge voltage of nearly lkV and is largely Independent of the electrode separation since the discharge is blown clear from the electrodes.
  • Breakdown of the electrode gap between the primary electrodes can be achieved at a reduced voltage by creating an emission site and/or ionised gas at one electrode with a separate discharge circuit and supply.
  • This is a 3 electrode form of a multiple electrode discharge similar to those used as pilot arcs in transferred arc plasma torches and discharge lamps.
  • the auxiliary discharge may be DC or AC although the use of DC eliminates effects due to variation in the phase angle between the two supplies. Such an arrangement is described in detail below.
  • the position of the third or auxiliary electrode is critical so as to prevent a conducting path to the main supply to the first and second electrodes, (which has a lower resistance than the electrode gap before breakdown), and it must also be positioned so as to prevent damage to the auxiliary electrode by the main discharge. This is achieved by locating the auxiliary electrode closer to one electrode than the other and can even be offset from the plane of the 2 electrodes.
  • Figure 1 is a circuit diagram of a VOC incinerator showing primary and auxiliary electrodes;
  • Figure 2 shows graphs of discharge voltage against discharge current for different electrode separations;
  • Figure 4 is a graph of discharge voltage against separation of primary electrode.
  • an incinerator 10 had two primary electrodes 12 and 14 and an auxiliary electrode 16. Electrodes 12 and 14 have a power supply 18. Electrode 14 is connected to power supply 18 via resistor Rs. A diode bridge 22 ensures current is delivered to auxiliary electrode 16 via resistor Rt from power supply 20. Gas to be ignited flows in the direction of arrow A..
  • Tests were carried out over a range of air flow rates of 5-10 1/min. Corresponding to an air velocity at the nozzle outlet of 24-48m/s.
  • the discharge current is almost sinusoidal and repetitive and was measured with an analogue meter.
  • the discharge voltage is very non sinusoidal and non repetitive with large extinction and ignition peaks. To overcome this the discharge voltage was derived from the current measurement since v d - oc " TMs
  • the first series of measurements were made of the discharge voltage and current characteristic across the primary electrodes (12 and 14) without auxiliary electrode 16 for a separation between the two electrodes (12 and 14) of 1mm and 2mm.
  • FIG. 3 shows dependence of discharge current (Ig) on voltage (Vg).
  • Ig discharge current
  • Vg voltage
  • the effect of the auxiliary electrode 16 is shown in Figure 4.
  • the separation between the primary electrodes 12 and 14 could be increased up to 12 mm before the arc no longer ignites.
  • the main discharge voltage was almost independent of the separation of the primary electrodes 12 and 14 which is consistent with the observations at electrode separations of 1 mm and 2 mm without an auxiliary electrode 16 as seen in Figure 2.
  • Figure 4 shows variation of separation rd with discharge voltage Vd. Tests were carried out to determine the effect of the auxiliary discharge between on the V-I characteristic of the main discharge, Figure 2 for separation of 2 mm and 4 mm of auxiliary electrode from the primary electrode. The results are similar to the discharge characteristic without the ignition electrode but at a much larger electrode separation and with greater discharge stability. The effect of the separation between the primary electrode and auxiliary electrode was not significant. A further series of tests at much larger separations of the primary electrodes ( Figure 2) at a constant separation between the primary and auxiliary electrode was carried out. Again this is largely independent of the separation between the primary electrodes but the voltage is higher and much more stable. A final test was carried out to determine the minimum voltage at which the discharge would ignite using an auxiliary electrode with and without a gas flow. The operating points for these conditions are shown in Figure 4.
  • the results show that the primary electrode 12 and 14 separation can be increased by using a third electrode 16 but the arc voltage only increases by a small amount.
  • the results also indicate that the supply voltage can be reduced to less than a half the value previously required, increasing the utilisation and reducing the loss in the power supply.
  • the separation of the primary electrodes is increased above the minimum value required for ignition, with no auxiliary electrode, the effect on the arc voltage is not so great and the discharge voltage is insensitive to the separation of the auxiliary electrode but increases with discharge current.
  • a fourth or higher order auxiliary electrode may be installed to a VOC incinerator.
  • a DC biassing voltage may be applied to the third or auxiliary electrode so as to ensure the required potential difference was present to initiate local ionisation.
  • This biassing voltage may be arranged to follow any variation in the potential difference across the primary electrodes.
  • the invention may be incorporated into an exhaust system of a vehicle.
  • a low-power arrangement may be fitted to the exhaust of a diesel powered vehicle such as an articulated lorry, in order to significantly reduce the exhaust emissions.

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

Abstract

L'invention a pour objet un appareil pour l'élimination de gaz nocifs, tels que des composés organiques volatils (COV), dans des émissions. Les dispositifs existants pour la réduction des COV comprennent deux électrodes en forme de surfaces plates coniques, sur lesquelles une différence de potentiel est appliquée. Le gaz contenant des COV passe entre les électrodes et, lorsque des COV sont détectés, ceux-ci sont incinérés dans la décharge, laissant ainsi moins de produits finaux nuisibles. Un inconvénient des dispositifs susmentionnés était que leur très grand besoin en puissance réactive, à cause de la tension d'amorçage nécessaire pour provoquer une décharge de l'ordre de plusieurs dizaines de kilowatts à la pression atmosphérique. La présente invention utilise une électrode auxiliaire (16) disposée entre deux électrodes (12 et 14) et un circuit de commande (18, 20 Rs et Rt) disposé de façon à réduire sensiblement la tension d'amorçage initiale et par conséquent la complexité, la consommation électrique et la capacité de puissance maximale de l'appareil.
PCT/GB1994/001818 1993-08-20 1994-08-19 Ameliorations de l'elimination de gaz nocifs dans des emissions WO1995006225A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB939317389A GB9317389D0 (en) 1993-08-20 1993-08-20 Improvements in removal of noxious gases from emissions
GB9317389.6 1993-08-20

Publications (1)

Publication Number Publication Date
WO1995006225A1 true WO1995006225A1 (fr) 1995-03-02

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PCT/GB1994/001818 WO1995006225A1 (fr) 1993-08-20 1994-08-19 Ameliorations de l'elimination de gaz nocifs dans des emissions

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GB (1) GB9317389D0 (fr)
WO (1) WO1995006225A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2717403A1 (fr) * 1995-03-10 1995-09-22 Czernichowski Albin Méthode d'élimination des hydrocarbures légers des mélanges gazeux.
WO2002000330A1 (fr) * 2000-06-30 2002-01-03 Electricite De France Service National Procede et dispositif de traitement par decharge electrique d'effluents organiques volatils gazeux
FR2817444A1 (fr) * 2000-11-27 2002-05-31 Physiques Ecp Et Chimiques Generateurs et circuits electriques pour alimenter des decharges instables de haute tension
EP1839318A2 (fr) * 2004-10-15 2007-10-03 Global Environmental Concepts, LLC Dispositif et procede de production de faisceau d'electrons a arc electrique
US8350190B2 (en) 2007-02-23 2013-01-08 Ceramatec, Inc. Ceramic electrode for gliding electric arc
US8618436B2 (en) 2006-07-14 2013-12-31 Ceramatec, Inc. Apparatus and method of oxidation utilizing a gliding electric arc
US8826834B2 (en) 2006-07-14 2014-09-09 Ceramatec, Inc. Apparatus and method of electric arc incineration

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE185897C (fr) *
FR566707A (fr) * 1923-04-19 1924-02-19 Procédé pour effectuer des réactions chimiques
SU1038381A1 (ru) * 1981-06-19 1983-08-30 Предприятие П/Я В-8916 Электродуговой испаритель
EP0343987A2 (fr) * 1988-05-26 1989-11-29 MITSUI TOATSU CHEMICALS, Inc. Appareil de traitement de gaz d'échappement
FR2666518A1 (fr) * 1990-09-12 1992-03-13 Mecanique Metallurg Ste Gienno Procede et dispositif de depollution de gaz pollues par des solvants.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE185897C (fr) *
FR566707A (fr) * 1923-04-19 1924-02-19 Procédé pour effectuer des réactions chimiques
SU1038381A1 (ru) * 1981-06-19 1983-08-30 Предприятие П/Я В-8916 Электродуговой испаритель
EP0343987A2 (fr) * 1988-05-26 1989-11-29 MITSUI TOATSU CHEMICALS, Inc. Appareil de traitement de gaz d'échappement
FR2666518A1 (fr) * 1990-09-12 1992-03-13 Mecanique Metallurg Ste Gienno Procede et dispositif de depollution de gaz pollues par des solvants.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 8423, Derwent World Patents Index; AN 84-144354 *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2717403A1 (fr) * 1995-03-10 1995-09-22 Czernichowski Albin Méthode d'élimination des hydrocarbures légers des mélanges gazeux.
WO2002000330A1 (fr) * 2000-06-30 2002-01-03 Electricite De France Service National Procede et dispositif de traitement par decharge electrique d'effluents organiques volatils gazeux
FR2810902A1 (fr) * 2000-06-30 2002-01-04 Electricite De France Procede et dispositif de traitement par decharge electrique d'effluents organiques volatils gazeux a basse pression et a basse temperature
US7417385B2 (en) 2000-11-27 2008-08-26 Ceramatec, Inc. Systems and method for ignition and reignition of unstable electrical discharges
FR2817444A1 (fr) * 2000-11-27 2002-05-31 Physiques Ecp Et Chimiques Generateurs et circuits electriques pour alimenter des decharges instables de haute tension
WO2002043438A3 (fr) * 2000-11-27 2003-01-23 Synergy Technologies Corp Systemes et procedes d'amorçage et de reamorçage de decharges electriques instables
US6924608B2 (en) 2000-11-27 2005-08-02 World Energy Systems Corporation System and method for ignition and reignition of unstable electrical discharges
EP1839318A2 (fr) * 2004-10-15 2007-10-03 Global Environmental Concepts, LLC Dispositif et procede de production de faisceau d'electrons a arc electrique
EP1839318A4 (fr) * 2004-10-15 2010-11-24 Global Environmental Concepts Dispositif et procede de production de faisceau d'electrons a arc electrique
US8618436B2 (en) 2006-07-14 2013-12-31 Ceramatec, Inc. Apparatus and method of oxidation utilizing a gliding electric arc
US8742285B2 (en) 2006-07-14 2014-06-03 Ceramatec, Inc. Method of oxidation utilizing a gliding electric arc
US8826834B2 (en) 2006-07-14 2014-09-09 Ceramatec, Inc. Apparatus and method of electric arc incineration
US8350190B2 (en) 2007-02-23 2013-01-08 Ceramatec, Inc. Ceramic electrode for gliding electric arc

Also Published As

Publication number Publication date
GB9317389D0 (en) 1993-10-06

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