RU2132238C1 - Gas cleaning apparatus - Google Patents

Abstract

FIELD: cleaning of gases from dust. SUBSTANCE: gas cleaning apparatus has source of alternating high voltage, system of plate plane-parallel precipitation electrodes which working surface is perforated and coated by dielectric. Precipitation electrodes are installed along flow of gas at variable distance between them thus ensuring alternation of disruptive gap to generate discharge plasma and main working gaps in specified numerical relation. Main working gap is filled with unipolar negative bulk charge produced due to extraction of charge carriers from zone of discharge plasma. EFFECT: increased corrosion resistance of apparatus in corrosive media and enhanced efficiency of trapping of dust. 2 cl, 2 dwg

Description

 The invention relates to techniques for cleaning gases from dust, as well as from the dispersed phase of associated liquids having a high polarity (solutions of acids, alkalis, salts, acids), and can be used in metallurgical, chemical and other industries.

 A device for dust removal of gases is known, including a plate-like precipitation electrode system and a system of ionizing electrodes made in the form of crossed rows of bare and dielectric-coated wires. When an alternating high voltage is applied to the system of ionizing electrodes, a discharge plasma arises between the rows of bare and insulated wires. Under the influence of a constant electric field, free charge carriers are removed from the discharge zone under the influence of a constant electric field.

 Dust particles are charged by electric forces, deposited on a precipitation electrode (SU, Copyright certificate N 956019, M. class. B 03 C 3/08, 1982).

 A disadvantage of the known device is the corrosion of metal precipitation and exposed ionizing electrodes during cleaning of aggressive media, as well as spark breakdowns between ionizing and precipitation electrodes.

 A device is also known for purifying gases from dispersed impurities, in which the gas stream to be cleaned is passed through the spark charge region and then fed to a system of plane-parallel precipitation electrodes installed along the gas stream at a working distance. Precipitation electrodes are coated with a uniform dielectric layer and connected to a high voltage alternating current source. The charge carriers charge particles of the dispersed phase, which under the influence of electric forces during a half-wave voltage are deposited on the precipitation electrode / JP, application N 22931, M, CL 72 C 54, 1968 /.

 However, the significant recombination rate of oppositely charged charge carriers at the outlet of the charger does not allow filling the space between the precipitation electrodes with a significant space charge. The efficiency of trapping dispersed impurities is low. In addition, in corrosive environments, corrosion of the metal electrodes of the arrester occurs.

 The problem solved by the described invention is to increase the efficiency of capture of particles of the dispersed phase in aggressive environments.

 To solve this problem, in a gas purification apparatus including a power source, an ionizer, a system of plate-like plane-parallel precipitation electrodes, perforated on the working surface, coated with a dielectric and installed along the flow at a working distance from each other, the precipitation electrodes are placed with a variable distance between them, providing the alternation of the breakdown charge to obtain a discharge plasma and the main working gaps in a given numerical ratio.

 In this case, the adjacent precipitation electrodes are connected to the opposite terminals of the high voltage AC source.

 The numerical ratio t of the alternation of the zones of the discharge plasma and the main working period is chosen in the range of values 1: 1, 1: 2, ..., 1: 5.

 The drawing shows a General view of the apparatus (Fig. 1A - t = 1: 1; Fig. 1B - t = 1: 3).

 The apparatus comprises a gas duct 1 in which a system of plane-parallel precipitation electrodes 2 with a dielectric coating 3 and perforated holes 4 is placed.

 Precipitation electrodes are placed alternately at a distance of the breakdown gap to obtain a discharge plasma 5 and at a distance of the main working gap 6.

 From the side of the working gap, the discharge zone is protected by a synthetic mesh 7 with a mesh size that is impervious to dust.

 The device operates as follows.

When applying an alternating high voltage between the precipitation electrodes, depending on their distance from each other, the electric field strength of the main working gap or the electric field strength (10 - 40) • 10 ⁵ V / m is generated to excite the discharge plasma.

 The charge carriers, extracted by the electric field through the perforated holes, fill the region of the main working gap with precipitation electrodes with a negative space charge. This is due to greater electron mobility and higher stability of negative ions at a given low thermodynamic temperature of the gas both in the discharge zone and in the working region.

 The action of a unipolar and space charge leads to the appearance of a sharply inhomogeneous electric field between the electrodes, which leads to the appearance of a resultant force acting on the dipole moments of dust particles arriving from the gas stream, polarized in an external alternating electric field, and tending to move them to a region with a higher intensity precipitation electrodes.

 Due to the coagulation occurring in the working space during the oncoming movement of aerosol particles, the dipole moment of the particles increases and their deposition improves.

 In the active zone of the proposed apparatus for gas purification, uniform deposition of both high-resistance dust and aerosols of associated liquids having a high polarity is carried out.

 The absence of open metal areas on the structural elements of the apparatus increases its reliability, corrosion resistance in aggressive environments and allows to increase the operating voltage.

 The low adhesion of many dielectric coatings improves the conditions for removing dust from the precipitation electrodes.

Claims (3)

 1. Apparatus for cleaning gases, including a power source, an ionizer, a system of plate-like plane-parallel precipitation electrodes, perforated on a work surface, coated with a dielectric and installed along the flow at a working distance from each other, characterized in that the precipitation electrodes are placed with a variable distance between them, while alternating the breakdown gap to obtain a discharge plasma and the main working gaps in a given numerical ratio.  2. The apparatus according to claim 1, characterized in that the adjacent precipitation electrodes are connected to the opposite terminals of the high voltage AC source.  3. The apparatus according to claim 1, characterized in that the numerical ratio of the alternation of the zones of the discharge plasma and the main working period is selected in the range of values 1: 1, 1: 2, ..., 1: 5.

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