SU1608499A1 - Method of measuring dispersed composition of course-dispersed aerosol - Google Patents

Abstract

The invention can be used in the metallurgy, building materials industry, medicine, and chemical industries to determine the dispersed composition of liquid and solid aerosols. The purpose of the invention is to improve the measurement accuracy. The aerosol particles are preliminarily charged (CHA), an aerosol (PA) stream is fed into a precipitation condenser (OK), in which the HAs are simultaneously subjected to alternating and constant electric fields transverse to the PA direction by applying an alternating voltage to the electrodes change, and the follow-up period is set smaller than the time of the PA through OK, and the constant voltage, and measure the charge of HA at the output of the OK at each fixed amplitude of the alternating voltage. The constant voltage is chosen from the condition of complete deposition on the electrodes of the NA with the lowest electrical mobility during the passage of the PA through OK. In OK, a steady spatial separation of the HA by size occurs, the selection of the HA fraction in a given size range, not deposited on the OK electrodes, and measurement of the total charge of the selected fraction, which is not affected by the fine fraction in an aerosol with a wide range of sizes. 4 il.

Description

3

to the electrodes of the precipitation condenser.

In the pipeline 1 (Fig. 1) of the isolation material, the charge chamber 2, containing two electrodes - a metal cylinder 3 and a metal needle 4 located on the axis of the pipeline 1 - is mounted in series along the direction of the flow of the aerosol under investigation; cylindrical electrode. 6 and a coaxially arranged internal cylindrical grounded electrode 7, and a measuring chamber containing a double helical electrode connected to the input of a variable current amplifier 10.

The method is carried out as follows.

The electrodes of the charging chamber 2 are supplied with pulsed unipolar radiation.

living and

them

10 V calling in

The negative pulse corona discharge in the interelectrode space. The aerosol particles passing through the charging chamber 2 during the pulse corona discharge acquire a negative electric charge. The flow of the aerosol leaving the charging chamber 2 is modulated by the bulk density of the electric charge with a frequency of 30 Hz. equal to the frequency of the voltage UHM.

Then the flow of aerosol with a volumetric rate of V 5 l / min enters the precipitation capacitor 5, in which the radius of the external electrode is 6 Kc 10 m, the radius of the internal electrode is 7 Rb 0.5 (and the length of the electrode is 1.3 m. To the electrodes of the precipitation condenser 5 apply a sinusoidal voltage with an amplitude of UQ 103 in J, a follow-up period T of 0.02 s (f 50 Hz) and a constant voltage of U 60 V. The flow time of the aerosol through the settling condenser 5 is 3.8 s. The aerosol particles, moving along electrodes 6 and 7, are displaced under the influence of The transverse to the direction of the flow of an aerosol of alternating and constant electric fields.Aerosol particles with radii less than 8.5 microns are deposited on the internal electrode 7, and particles with radii greater than 9.5 microns are deposited on the external electrode 6 of the precipitation condenser 5.

ten

15

20

25

thirty

35

40

five

After the precipitation condenser 5, an aerosol stream containing particles in the size range of 8.5–9.5 µm enters the measuring chamber 8. The passage through chamber 8, the charged aerosol particles, are injected into the cylindrical electrode 9 by a variable electric charge proportional to the counting the concentration of N particles in the size range of 8.5-9.5 microns.

By applying a sinusoidal voltage with an amplitude of Uo 210 B to the electrodes 6 and 7 of the precipitation capacitor 5 with the remaining unchanged parameters, the aerosol particles are installed in the 5.5-8 µm size range. Measuring the charge of the particles at the outlet of the precipitation condenser 5 at Ug 2-103 V is obtained

the signal is proportional to the counting concentration of N particles in the size range 5.5-8 microns.

With an amplitude Uo of sinusoidal voltage equal to 310 V, aerosol particles are installed in a size range of 4-6.0 µm.

Measuring the charge of the aerosol particles at the outlet of the settling capacitor 5 at each fixed value of the amplitude UQ of the sinusoidal voltage, we obtain the size distribution function of the particles (Fig. 2).

The period T of the sinusoidal voltage following is 0.5% of the time t pp of the aerosol flow through the precipitation condenser 5. At the same time, the jb efficiency for the separation of a given fraction of particles was close to unity. I

The coefficient K p of the leakage of particles in the fraction fraction (a, a) through the precipitation condenser 5 is determined by the expression

N N

to p

0

five

Where

Xt

N and

N is the apparent concentration of aerosol particles before and after the precipitation condenser 5.

FIG. Figure 3 shows the dependences of the particle slip factor on their size, obtained for different values of the amplitude Vg of the sinusoidal voltage and the remaining unchanged parameters: U 60 V, T 0.02 s, tnp 3.8 s.

As shown by experiments, when

the geometrical dimensions of the precipitation capacitor 5 (Ru 10

Ri 0,5-10-2

aerosol flow rates (V

fc nna

 5 l / min), choosing a constant voltage and 60 V, ensured complete deposition of particles with a radius of 1 μm, including particles with a radius of 0.1-0.3 μm with the lowest electrical mobility (Fig. H)

In addition, the investigated dependency.

L 1,3 m) and constant

bridge

VW - J- -w- -w. to l-fJ f .4 i n with.

capacitor 5 particles of aero-, 5 unipolar ions, flow

Its size is different at different values of constant voltage U. With this purpose, in a precipitating capacitor 5 with a radius of the external electrode 6 of it, drop to the electrodes of a sinusoidal 10 m and a radius of the internal 20 of the electrode 7 R 0.5. the time t of deposition in the precipitating method of measuring the dispersed material of coarse-dispersed aerosol, including the preliminary charge of aerosol particles in shock mode

c / o & amplitude amplification Uo jf 2-1 Р В and the follow-up period T 0.0 s (f 50 Hz), For values of 25 constant voltage applied to the electrodes of the settling contrg part of the aerosol

Densa-ora 5, U 20 V; 60 V received for: the value of their size (figure 4),

Kai: showed experiments with dunn; the geometrical dimensions of the precipitation condenser and the given flow rate of the aerosol under study, selecting a constant voltage and, they say: ensure complete precipitation of particles with a 1 μm, including hours with 0.1-0.3 μm, possessing With their lowest electrical mobility, during the passage of a stream of aerosol through a precipitation condenser 5-. In this case, in the measured charge of aerosol particles at the exit from

thirty

35

40

an aerosol into a precipitation condenser; an impact on charged aerosol particles by an alternating electric field transverse to the direction of the aerosol flow; by applying alternating alternating voltage to the precipitation condenser electrodes, the amplitude of which is changed, and measuring the charge of aerosol particles at the outlet of the precipitation condenser at each a fixed value of the alternating voltage amplitude, characterized in that, in order to improve the measurement accuracy, the alternating voltage follow-up period is set It is shorter than the time of the aerosol flow through the precipitation condenser, and simultaneously with the alternating field the particles are charged charged transversely to the direction of flow by a constant electric field, the value of which is chosen from the condition of complete deposition on the electrodes of the aerosol particles with the least electrical mobility during time passing the aerosol stream through a precipitation condenser.

 - J- -w- -w. to l-fJ f .4 i n with.

, 5 unipolar ions, flow

84996

precipitation condenser 5 excl. 10

The contribution of the particles of the fine fraction (axil µm), which provided an increase in the accuracy of measurement of the dispersed composition of the coarsely dispersed aerosol under investigation.

Claims (1)

Invention Formula A method for measuring a dispersed state of a coarse aerosol, including preliminary charging of aerosol particles in a shock mode 5 unipolar ions, flow 20 five 0 five 0 the aerosol into the precipitation condenser, the effect on the charged aerosol particles transverse to the direction of the aerosol flow by an alternating electric field by applying alternating alternating voltage to the electrodes of the precipitation condenser, whose amplitude is varied, and measuring the charge of the aerosol particles at the outlet of the precipitating condenser at each fixed the magnitude of the alternating voltage, characterized in that, in order to improve the measurement accuracy, the period of the alternating voltage of the The aerosol is smaller than the flow time of the aerosol through the precipitation condenser, and simultaneously with the alternating field, the charged particles are transverse to the direction of flow by a constant electric field, the magnitude of which is chosen from the condition of complete deposition on the electrodes of the aerosol particles with the smallest electrical mobility during the passage time Aerosol flow through a precipitation condenser. 5 6 L .  77 / 9Z ) (A ( Uum. . U (i) -UW5incJt 1 8 9 / n. 70 UQ- З-Ю В / -ZHz (G-OMS) .8C Uo - 2-lO B UO - IO B 70 NCC Phage. 2 About 1 -50Hz1t 0.02s} 8c 9 10 microns Fig.Z 0.001 0.01 Vo- 2 10 e, Q2), OlM KB 0.005m 0.1 W FIG.