FR2613254A1 - Electrostatic filter operating by wet route - Google Patents

Abstract

The invention relates to a gas-filtering device using a wet electrostatic filter, comprising at least one ionising electrode 5 inserted between two or more collecting electrodes made from incombustible synthetic or metal fabric 4 which suppress the preferential currents upon passage of the scrubbing (washing) liquid 3. A high-voltage generator 8 supplies the ionising electrodes 5 which may be subject to electrical arcs which will be detected immediately by an electronic system 9, 10, 12, 13 connected to an optical fibre 11.

Description

WET ELECTROFILTER
The invention relates to a device intended in particular to improve the collection of solid and liquid particles in a wet electrostatic precipitator.

 To retain the particles in a gas flow, the ionization crown effect is already used to bond the dust to the walls of the filter.

 The elimination of these is already carried out by trickling of liquid on the collestice walls, progressively covered with particles extracted from the treated gas flow. To achieve such a result, the prior art proceeds by spraying liquid on the electrode collar-reader or by simple trickling.

 These different techniques have the drawback of the risk of creating an electric arc during the spraying of the liquid or of preferential chemistry followed by the cleaning liquid during runoff.

 The present invention remedies these drawbacks of the prior art. Indeed, the collector electrode no longer consists of a rigid wall cleaned more or less rigorously, but by the liquid which, in permanent contact with the mass of the voltage generator, circulates in the electrofilter by soaking in a fabric synthetic fire retardant or metallic as support.

 One of the advantages of this invention is that there is no longer any preferential path because the entire tissue is soaked with liquid and acts as a collecting electrode.

 The liquid arrives at the top of the electrostatic precipitator and circulates in a perforated tubular bundle which serves both to impregnate and to maintain the tissue.

 It is also possible, to remove the preferential paths which are created in the small cylindrical electrostatic filters by wet method, to insert a stainless metallic fabric which, by its elasticity will deploy and will be applied perfectly. On the internal wall of the cylinder.

 The configuration of the filter of the present invention is as follows: - A series of parallel corridors, through which the gases pass, are formed by the strips of fabric respecting between them a difference of 80 to 100 min.

 The ionizing wire electrodes are arranged at regular intervals in the center of the corridors. Bnpoussi'erés gases preferably arrive from the bottom of the electrostatic precipitator, disperse in the vertical corridors formed by the strips of fabric, and come out purified by 1 Crown effect, at the top of the electrostatic precipitator.

 The wire electrodes are connected to the high voltage generator. Advantageously, this high voltage generator is of the type comprising, in series, a low voltage oscillator, a current chopper, and an induction coil or the like, comprising a primary winding connected to the output of the chopper and a secondary winding connected by a high voltage diode at the electrode rani'erse of the ionization enclosure.

Such a high voltage generator has a low cost price.

 The accidental creation of an electric arc inside an electrostatic precipitator is detrimental to the proper functioning of the latter.

A simple control system can be realized by fixing on the high voltage line a neon coupled in parallel with a resistance of about 470 ohms. When an electric arc is created, by current return and by potential difference, the neon lights up immediately. This weak signal can be perceived and increased by means of an electronic amplifier attached to the other end of the optical fiber which will advantageously be made of plastic. This amplifier will include a photo-transistor which will pierce the light signal emitted and will strongly amplify it in the form of an electric pulse which can activate a light or sound signal.

Other details, advantages and characteristics of the invention will appear on reading the description which follows, given by way of example with reference to the appended drawing and in which:
- Figure 1 schematically shows a liquid runoff device according to the prior art.

 - Figure 2 schematically shows an irrigation device according to the invention.

 - Figure 3 is a schematic view in longitudinal section of the ionization and filtration enclosure.

 - Figure 4 is a schematic view of the whole system comprising the collecting electrodes (Figure 2), the ionizing electrodes 5, the high voltage generator 8, the control system with optical fiber (9 to 13).

Referring to Figure 2, we can see an example of the device which represents, in section, two tubes (1, perforated with a large number of holes (2), used to bring and distribute the liquid (3) collector particles, and also serving to keep the synthetic or metallic fabric (4) stretched vertically.

FIG. 3 is a diagram in longitudinal section of the ionization enclosure where the particle collection device shown in FIG. 2 is associated with the ionization electrodes (5).

FIG. 4 is a block diagram of the wet electrostatic precipitator where the collection electrodes (4) are sufficiently spaced to allow good ionization of the gases thanks to the ionizing electrodes (5).

The high voltage generator is represented in (8), associated with the control system comprising a resistor (9), associated with a neon (10), on which is fixed an optical fiber (11), which receives the light signals coming from the neon to transmit them to a receiver-transmitter (12), which can activate a light or sound signal (13).

Claims (6)

 1- Wet electrostatic precipitator for the collection of solid or liquid particles contained in a gas to be purified, comprising at least one ionization electrode and a collecting electrode characterized in that the collecting electrode is formed by a flow of liquid, connected to a high voltage generator terminal, and by a flame retardant or metallic fabric impregnated with the liquid.  2- Device according to claim 1 characterized in that the aforementioned fabric is supported by a perforated tube forming part of the means for supplying the liquid flow.  3- Device according to any one of the preceding claims, characterized in that the fabric walls are arranged together so as to produce wet particle-collecting corridors, separated from one another by a distance of a few tens of millimeters, and preferably from 80 to 100 millimeters to respect good ionization of the gas to be treated with a good passage speed.  4- Device according to any one of the preceding claims, characterized in that the ionizing electrodes are wired and located in the center of the wet corridors on the same axis.  5- Device according to any one of the preceding claims, characterized in that the high voltage generator which supplies the ionizing electrodes is of the type comprising in series, a low voltage oscillator, a current chopper, and an induction coil or analog, comprising a secondary winding connected by a high voltage diode to the first electrode of the ionization enclosure.  6- Device according to any one of the preceding claims, characterized in that a simple control system makes it possible to detect the accidental creation of an electric arc harmful to the proper functioning of the filter by using in series, fixed on the high line. voltage, a neon coupled in parallel to a resistor of about 470 ohms, an optical fiber fixed on the neon which will capture the Lux, and a repeater amplifier fixed on the other side of the optical fiber which will capture by means of a photo- transistor the signal and will amplify it by transforming it into an electric pulse which can activate a light or sound signal.