RU2763129C1 - Device for measuring the specific charge of aerosol particles - Google Patents

Abstract

FIELD: aerosols.

SUBSTANCE: invention is intended for measuring the specific charge of aerosol particles. The substance of the invention lies in the fact that the device for measuring the specific charge of aerosol particles contains a sampling unit and an electrostatic voltmeter, while the sampling unit consists of an external housing, grounded to exclude the influence on the measurement result of free ions and electrically charged particles deposited on the device, and the inner case, isolated from the outer case by fluoroplastic bushings, containing sequentially placed metal grids in contact with it, on which a filter-absorbent material is located to capture particles of both liquid and solid charged aerosol and determine their mass, while the charge of aerosol particles seeded on the filter-absorbent material is transferred by the meshes to the inner case, the potential of which is measured by electrostatic voltmeter.

EFFECT: ensuring the possibility of measuring the specific charge of both solid and liquid aerosol particles during their electric charging, including in the field of a corona discharge.

1 cl, 1 dwg, 1 tbl

Description

The invention relates to measuring equipment and can be used in electro-gas cleaning, chemical industry and electronic-ion technology for measuring the specific charge of aerosol particles.

Known installation (G.P. Samkharadze, Y.S. Monin, I.Sh. Kokaya Methodology for measuring the magnitude of the charge of polymer powders [Text] // Paints and varnishes and their application, Publishing House "Chemistry". - 1976. - No. 5), allowing to measure the charge acquired by particles in a fluidized bed, and consisting of a measuring plate inserted into a dielectric holder, connected by clamping contacts with a shielded cable through a switch with an electrostatic voltmeter.

The disadvantage of this installation is that when determining the specific charge, it is necessary to know the mass of the particles seeded on the plate, which is determined by the difference in the mass of the clean plate and with the powder sown on it. Liquid particles, when the measuring plate is located perpendicular to the flow of charged particles, will drain from it. In addition, in the case of external charging by a corona discharge, in addition to charged particles, the aerosol flow also contains ions formed during corona treatment of high-voltage electrodes. This leads to an overestimation of the measured value.

The closest to the proposed invention is a device for measuring the charge of particles of a powder material (inventor's certificate for invention No. 1004902 dated 03/15/1983), containing a working chamber made of dielectric material, inside which electrodes equipped with a dielectric coating are installed, a sample suction unit connected to the working chamber, at the opposite end of which there is a tip with an opening for introducing particles of the studied powder material, while a dielectric insert is placed in the working chamber behind the electrodes in the direction of movement of the particles in such a way that it divides this part of the chamber into two channels, at the exit of which measuring electrodes connected to the recording device, measuring electrodes are made in the form of metal cylinders installed with a gap relative to the channel walls, mounted with the possibility of rotation around their axis and equipped with a drive, and the suction unit is equipped with brushes in contact with the surface the said cylinders along their entire length from the side of the suction unit, while in the channels there are sensors of the particle flux density connected to the said recording device, for example, a loop oscilloscope.

The disadvantage of this device is its unsuitability for measuring the specific charge of liquid particles due to their inevitable deposition on high-voltage electrodes, as a result of which not the entire flow of particles reaches the measuring electrodes, which will introduce a significant error in the measurement result.

The objective of the present invention is to provide the ability to measure the specific charge of both solid and liquid aerosol particles when electrically charged, including in the field of a corona discharge.

The problem is solved by the fact that in the proposed device for measuring the specific charge of aerosol particles containing a sampling unit and an electrostatic voltmeter, the sampling unit consists of an external housing, grounded to exclude the influence on the measurement of free ions and electrically charged particles deposited on the device, and an internal a casing isolated from the outer casing by fluoroplastic bushings, containing sequentially placed metal grids in contact with it, on which a filter-absorbent material is located to capture particles of both liquid and solid charged aerosols and determine their mass, while the charge of aerosol particles seeded on the filter-absorbent material, is transmitted by the grids to the inner case, the potential of which is measured with an electrostatic voltmeter. The accumulated charge in this case will be equal to

where C _p is the capacity of the sampler, F;

C _in - the capacity of the electrostatic voltmeter, F;

U is the potential measured by an electrostatic voltmeter, V.

The filter-absorbent material is quantitatively analyzed to establish the mass of the collected charged aerosol.

The specific charge is determined in accordance with the formula

where m is the mass of the selected electrically charged aerosol, g.

The essence of the proposed device for measuring the specific charge of aerosol particles lies in the placement of a filter-absorbent material for capturing both liquid and solid particles on metal grids in the inner case of the sampling unit, which serve to transfer the particle charge to this case, the potential of which is measured by an electrostatic voltmeter connected to it. To exclude the influence of free ions formed in the corona discharge field, the inner case is located inside the grounded outer case, isolated from it by fluoroplastic bushings.

FIG. 1 shows a device for changing the specific charge of aerosol particles, which contains:

1 - outer case;

2 - fluoroplastic bushing;

3 - inner case;

4 - filter-absorbing material;

5 - metal mesh;

6 - fitting;

7 - clamping screw.

The principle of operation of the device for measuring the specific charge of aerosol particles is as follows: the device is placed in a stream of electrically charged aerosol, where free ions are deposited on the grounded outer casing (1), thereby eliminating the influence on the measurement of the specific charge, charged aerosol particles during forced suction through the inner casing (3), connected by a vacuum hose through the fitting (6) to the aspiration device, and isolated from the external one by fluoroplastic bushings (2), passing through the metal mesh (5), fall on the filter-absorbing material (4), transferring the particle charge through the metal mesh (5 ) and the inner case (3) through the clamping screw (7) of the electrostatic voltmeter.

Using the proposed device, the diagram of which is shown in Fig. 1, a number of experiments were carried out to determine the specific charge of aerosols in a liquid formulation based on dibutyl phthalate generated by a pneumatic generator and powdered solid anthracene created by thermal sublimation. The particles were charged in a corona discharge field at a potential applied to the corona electrode of 20 kV. Aerosol samples were taken from the flow onto the sorbing material using an M-822 (A) aspirator. The voltage created by charged particles on the grids and the inner case of the device for measuring the specific charge of aerosol particles was recorded with an S-511 electrostatic voltmeter. The results of experimental studies are presented in table 1.

Analysis of the data presented in Table 1 shows that during the research, free ions were completely "cut off" from the measurement zone, as indicated by the zero readings of the electrostatic voltmeter. The developed sampling device makes it possible to effectively determine the specific charge of both liquid and solid aerosols.

The alleged positive effect of the claimed invention is to ensure the determination of the specific charge of particles of both liquid and solid aerosols and to exclude the influence of free ions on the measurement result.

Claims (1)

A device for measuring the specific charge of aerosol particles, containing a sampling unit and an electrostatic voltmeter, characterized in that the sampling unit consists of an external housing, grounded to exclude the influence of free ions and electrically charged particles deposited on the device on the measurement result, and an internal housing isolated from the outer casing by fluoroplastic bushings containing sequentially placed metal grids in contact with it, on which a filter-absorbent material is located to capture particles of both liquid and solid charged aerosol and determine their mass, while the charge of aerosol particles seeded on the filter-absorbent material is transferred by the nets to the internal enclosure, the potential of which is measured with an electrostatic voltmeter.

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