SU1437746A1 - Method of determining fraction sizes of coal-water aerosol - Google Patents

Abstract

The invention relates to: the field of optics of dispersed media and allows determining the concentrations of two fractions of a coal-water aerosol with high accuracy. The purpose of the invention is to expand the information content and improve accuracy. To do this, measure the attenuation of the probing radiation in the visible region of the spectrum passing through the volume of the test medium, and at the same time the degree of linear polarization P of the radiation scattered by the aerosol in the direction constituting 60 - 20 ° C. with the direction of the probe radiation. Desired concentrations — total geometric sections of coal dust particles S to water droplets S per unit are determined from the ratios Si volume – 7 A (HB (a – P) / (P – b)) 1; C + (P-b) 7 B (a-P)), where A, A B, a. в, - constant calibration coefficients. 3 silt o (L

Description

four

WITH

4: O)

The invention relates to the control-} 1O-measuring technique, in particular to the optical methods for the control of dispersed media, and can be used in the coal mining or mining industry during dust suppression using water aerosol

The purpose of the invention is the expansion of informativeness and accuracy

Figure 1 shows the angular dependences of the degree of linear polarization of light scattered by coal and particles when sounding a carbon-water dispersed medium by a light beam with a wavelength of 0.55 μm (curve 1 corresponds to coal particles with a size of 1.2 μm, curve 2 —particles with a size of 2.4 microns, curve 3 —particles with a size of 8.8 microns in FIG. 2 — the experimentally obtained dependence of the degree of linear polarization of the light scattered by the coal particles, on the fractional fraction of the coal water aerosol at an angle of dispersion of 50 (curve 4 soo corresponds to water aerosol particles with an average size of 6.0 μm, curve 5 to water aerosol particles with an average size of 15 μm); Fig. 3 is a block diagram of an apparatus for carrying out the method for determining the fractional composition of a coal-water aero3 OLYA "

The device contains a source 6 of a probing light beam, a study volume 7 with a coal-water aerosol, a photodetector 8, a polar field. meter 9 and block 10 information processing.

The essence of the invention is as follows.

Experimentally established a strong difference in the angular dependences of the degree of RSb) linear polarization of scattered radiation for particles of coal and water particles. At a scattering angle of 40 to 80 °, the maximum difference in the degree P (9) of linear polarization is observed for both types of particles.

In this case, for particles with a size greater than 1.5 μm, the value of P (b) is weakly dependent on the size of the particles (FIG. 1). Therefore, measurements of the degree of linear polarization at these angles can serve as Э (| x}) as an effective measure of the fractional composition of the sample.

my environment, defined by the ratio, where 5jj is the total geometric cross section of water droplets per unit volume; S is the total geometric section of the coal particles in units of volume (figure 2).

For a mixture of coal particles with water, the values of the degree P (b) of linear polarization can be represented as

P (s) Si2 (0) Pt (e) (6) P. (6) t5t5Q f (0) +)

(one)

where Q (9) and (Q) p. (e) and Pb (0)

about

averaged over the particle size spectrum, the efficiency factors of light scattering in the Q direction for coal and water particles, respectively; degrees of polarization, respectively, for coal and water aerosol.

Since these values tend to their asymptotic values with increasing size, they can be approximately considered as constants.

The attenuation index 5 of the probe light beam is determined by the expression

Yg

S,

Qb "

(2)

where Q. and (X are, respectively, averaged over the particle size spectrum, the factors eff (weakening interactions about

Then, from the expressions (1) and (2), the basic relations used for analyzing the fractional composition of the medium can be obtained:

50

, (, .в-5.Ш) -., -i E / A4-- | --- iH

(3)

where a, a, b, a, b (4)

constant calibration coefficients.

where

BUT

Q.; - A

Q

You are t...

Qb (0) Q

a, b Pj (e)

A device for carrying out the proposed method (Fig. 3) works as follows.

The probing light beam from the source is directed into the investigated volume with a coal-water aerosol. The transmitted light is recorded by a photodetector, the output signal of which determines the attenuation indicator 8 of the probe beam of light. Polarized radiation scattered by the volume under study is recorded with a polarimeter oriented at an angle b from 40 to 80 relative to the direction of propagation of the probe beam.

The measured values of the parameter B, the attenuation of the degree of linear polarization, are transmitted to the information processing unit, where the calculated concentrations of both fractions are determined using the calculation formulas (3) and (4).

Claims (1)

Formula of the invention The method for determining the fractional composition of the coal-water aerosol. including probing a carbon-water aerosol with a light beam in the visible spectral range, measuring the intensity of a light beam transmitted through a coal-water aerosol, and determining the attenuation indicator 5 of the probing light beam, characterized in that, in order to increase the information content and increase accuracy, the degree of P {0,). Linear polarization of the light scattered by the carbon-water aerosol in the direction constituting angle b is from 40 to 80 with the amplitude of the propagation of the probing light beam, and The mm geometrical cross sections of S and and Sj of coal dust particles and, respectively, of water droplets are determined from the ratios 25 S,. (T.B- |: | ifii-), c- C / Gl / P (e.) - h1 s (n-5 Ce, J where a, a, b, a, b - constant calibration factors. ig.1 FIG. g te-j