KR20010031254A - Device for plasma processing of gases - Google Patents

Abstract

The present invention relates to an apparatus (1) for treating a gas medium with a plasma, comprising one or more electrodes held in place relative to the other by one or more insulating support structures (7, 8) made of mica-containing glass material ( 6, 14).

Description

Device for plasma processing of gases

In particular, such devices used for the exhaust gas treatment from internal combustion engines are to be operated in very harmful environments. This means that there is a special requirement for the insulating support structure for the electrode, which requirement must be chemically inert, capable of withstanding significant chemical and mechanical shock, intermittent or continuous tens of kilovolts. It must be able to withstand the potential of. Ceramic materials such as alumina have been used in the manufacture of support plates, and although they are satisfactory in terms of chemical inertness and insulation properties, they tend to be brittle and rupture.

TECHNICAL FIELD The present invention relates to an apparatus for treating a gas medium with a plasma, and more particularly, to an apparatus in which one electrode is axially located within another electrode.

1 is a schematic longitudinal sectional view of an apparatus for treating contaminants to remove contaminants from an internal combustion engine;

According to the present invention there is provided an apparatus for treating a gaseous medium with a plasma, the apparatus comprising one or more electrodes held in place relative to each other by one or more insulating support structures made of micaceousb glass material. It is included.

It is preferable to use the mica-containing glass material manufactured under the trade name MICATHERN from Morgan Matlock Limited, a subsidiary of Morgan Crucible Company.

Preferably, the electrode or metal attachment member for the electrode is fixed to the insulating support by molding the support material on the electrode or metal attachment member in place. In this way the insulating support and the electrode attached to the insulating support directly or via a metal attachment member can be formed as an independent unit that can be removed and replaced. In such units, it is preferred that the pair of insulating supports and the pair of electrodes form a gap therebetween, the gap being filled with pellets of the active material.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 1, there is shown a reactor for removing contaminants such as NO _x or carbonaceous combustion products from exhaust gas from an internal combustion engine consisting of a cylindrical stainless steel chamber 2, wherein the cylindrical stainless steel chamber 2 is illustrated. Is equipped with an inlet stub 3 and an outlet stub 4, which can be connected to the exhaust system of the internal combustion engine. The chamber 2 is arranged to be connected to the ground point 5 in use. Each of the perforated inner and outer cylindrical electrodes 6, 14 is coaxially positioned in the chamber 2 by two supports 7, 8. The external electrode 14 is connected to the grounded chamber 2 and maintained at ground potential. The upstream of the internal electrode 6 is closed and can be arranged to be connected to a pulsed or continuous power source 9 on the order of tens of kilovolts via the insulated supply passage 10. In the gap 11 formed between the outer electrode 14, the inner electrode 6, and the supports 7, 8, the pellet bed 12 of the active material including ferroelectric material such as barium titanate or made of ferroelectric material Is filled. The upstream support 7 has a series of holes 13 formed therein, but the support 8 is impermeable. The choice of material composition of the pellets and the mode of operation of the reactor 1 are also determined on the basis of the contents illustrated in the examples described in the applicant's international patent application PCT / GB98 / 02569.

The supports 7 and 8 are made of lead-based glass with mica diffused therein. The material sold by Morgan Matlock Limited under the trade name MICATHERM is particularly suitable for the use of the present invention, because it can withstand the operating environment of the internal combustion engine exhaust system, has the necessary electrical properties as well as resistance to thermal shock. It is because it has and can shape | mold easily to a required shape by a shaping | molding technique.

In particular, the material can be molded directly onto the metal component and form a bond that is firmly bonded and sealed with the metal component. This is illustrated in the embodiment shown in the figure in which each support 7, 8 is molded on a pair of concentric cylindrical metal stubs 71, 72 and 81, 82, respectively. The stubs 71, 72 and 81, 82 are firmly fixed and sealed to the respective supports 7, 8 and provide attachments for the electrodes 6, 14. Thus, the internal electrode 6 is made of a somewhat larger radius than the stubs 71 and 81, so that it is pushed onto the stub and firmly attached to them in any suitable manner (eg welding). . The external electrode 14 is similarly fixed on the stubs 71 and 82.

In this way, a complete set of components comprising the supports 7, 8, the electrodes 6, 14 and the pellet bed 12 form a standalone unit that is removable and replaceable, which is referred to as " cassette " for convenience. Filling or recharging the pellets is possible by using one or more removable plugs (not shown) in the supports 7 and / or 8.

The invention is not limited to the details of the embodiments described above. By way of example, the feed passage 10 need not necessarily be located on the side of the chamber 2 but may be positioned to extend through the end wall.

Claims (6)

1. An apparatus for treating a gaseous medium by a plasma comprising at least one electrode 6, 14 held in place with respect to the other electrode 6, 14 by at least one insulating support structure 7, 8. The support structure (7, 8) is characterized in that it is made of micaceous glass material. The gas medium processing apparatus of claim 1, wherein the mica-containing glass material is sold under the trade name " MICATHERM " by Morgan Mattlock Limited. 3. Apparatus as claimed in claim 1 or 2, which is adapted to form part of an exhaust system of an internal combustion engine. The electrode (6, 14) or metal attachment member (71, 72, 81, 82) for the electrode (6, 14) or the metal attachment member (71) according to any one of claims 1 to 3. And 72, 81, 82 on the support material (7, 8) by molding the support material in situ. 5. The electrode (6, 14) of claim 4, wherein the electrodes (6, 14) attached to the insulation support (7, 8) and the insulation support directly or via a metal attachment member (71, 27, 81, 82) are removable and replaceable. A gas medium processing apparatus, comprising a stand-alone unit. A pair of insulating supports (7, 8) and a pair of electrodes (6, 14) form a space (11) therebetween, The space is filled with pellets (12) of the active material.