SU1054743A1 - Device for determining range of dimensions of aerosol particles and concentration of aerosol - Google Patents

Abstract

DEVICE FOR DETERMINATION OF THE DISPERSITY AND CONCENTRATION OF AEROSOL, containing the source of collimyro / i4S LU. / ..;.,, r.; g VV of the bathing beam of light, and measuring volume, the site of sight of the light scattered by the aerosol, installed with the possibility of angular displacement relative to the collimated beam of light, the polaroid, light filters, the photodetector located on the path of the collimated beam of light, Adjustable brightness screen and photodetector located in the sighting unit, I can distinguish 1; | iis that, in order to improve measurement accuracy in the expanded concentration range and dispersion of the aerosol, the candlestick with adjustable brightness audio and a photodetector disposed on the optical axis perpendicular to the axis (A unit of sight, and the point of intersection of sight axis of the assembly and the optical axis of a reflector having two reflecting surfaces and the slits serving to form the floor cf. gvneni. eaten 4 vj :)

Description

The invention relates to a measurement technique and can be used in printing, medicine, energy for the study and control of aerosols, including aerosol pollutants from industrial ventilation emissions.

Devices are known for measuring the dispersion and concentration of aerosol particles containing a source of collimated light beam propagating through the aerosol, photodetectors of light scattered by the aerosol in a given direction and attenuated by the aerosol, light filters, polaroids installed on the light propagation paths l and 2

The disadvantages of such devices are the low sensitivity of the measurements due to the impossibility of separating the signal and the background component of the photodetector current, as well as the narrow range of current measurement of the photodetector and, accordingly, the concentration of aerosol particles.

Closest to the present invention is a device for determining the dispersion and concentration of an aerosol containing a source of collimated light beam, a measuring volume, an assembly for sighting light scattered by an aerosol, mounted for angular movement relative to a collimated light beam, polaroids, light filters, a photodetector located on the way a collimated beam of light, a screen with an adjustable luminosity, and a photodetector located in the sighting unit Z.

Disassembling and replacing its assembly is necessary for calibrating this instrument. The instrument does not allow measurements of the scattered light by a photoreceiver and visually without disassembling and replacing the instrument assemblies, reducing the accuracy of aerosol measurements and complicating the operation of the instrument. .

The aim of the invention is to improve the accuracy of measurements in the extended range of concentration and dispersion of aerosol.

The goal is achieved by the fact that in the device for determining the dispersion and concentration of an aerosol containing a source of collimated light beam, a measuring volume, an assembly for sighting light scattered by an aerosol, mounted for angular movement relative to collimated light, polaroids, light filters, and a photodetector located on the way collimated beam of light, a screen with adjustable brightness and a photodetector located in

the sighting assembly, a screen with adjustable luminosity and a photodetector are located on the optical axis perpendicular to the axis of the sighting assembly, and at the intersection of the axis of the sighting assembly and the optical axis there is a reflector with two reflective surfaces and slots to form a comparison field.

Such an arrangement of the reflector with slits simultaneously ensures the passage of scattered light to the photodetector of the sighting unit, observation of the measurement volume of the aerosol diffusing light, and the screen with adjustable brightness.

The device operates in the most optimal mode (it provides the greatest accuracy of comparison of the velocities) when the distances from the screen with an adjustable luminosity and measurement volume to the reflector are equal.

FIG. 1 shows a diagram of the device; in fig. 2 is a view of the reflector, section A-A in FIG. one.

The device contains measuring volume 1; in this version, the extrude is a section of the exhaust pipe, a source of collimated light beam 2 (for which a laser can be used), a sighting device 3, a reflector 4 with two reflective surfaces and slots to form comparison fields, photodetectors 5-7, light filters 8–10, half 11, 12, diagram 13, lens 14, screen with adjustable luminosity 15, power sources 1618, test equipment 19 for measuring photocurrent currents 5–7 and t Eye of the light source for the screen 15, the angular scale 20 of the movement of the sighting device.

The distances between the screen 15 and the mirror 4, as well as between the displayed aerosol and the reflectors 4 are respectively equal.

The device works as follows.

The collimated beam of light from source 2 is divided into two parts. The first is directed to the photodetector 5, and the second to the aerosol passing through the measuring volume 1 and into the photodetector 6. The light scattered by the aerosol, at a given angle, enters the sighting device 3, where, reflected from one of the surfaces of the reflector 4 It is directed to the photodetector 7. The intensity of the scattered light is measured by the current of the photoreceiver 7. Part of the scattered light passes through

the slits of the reflector 4 to the observer for comparing the brightness of the light -. Vanos aerosol and luminance of the screen image 15.

The last image is formed using the second reflecting surface of the reflector 4.

To measure the luminance characteristic of the screen 15 (instrument calibration), a photodetector 7 with lens 14 is used with the reflector 4 removed.

The intensity of light scattered by an aerosol at a given angle, at low concentrations, is measured by the current of the light source illuminating the screen 15, converted to the current of the photodetector 7 by the light characteristic of the screen brightness 15. In this case, the dispersion of the aeroeol particles is determined by the family of calculated indicatrices scattered no light, and concentration - according to the dispersion obtained and the currents of the photodetectors b and 7; the calculation is carried out according to the well-known methodology.

At high concentrations, the aerool intensity of the scattered light is measured directly from the current of the photodetector 7, and the light source of the screen 15 must be turned off, and the dispersion of particles is also determined by the family of calculated scattering indicatrices. no light. The use of two photodetectors 5 and 6 for measuring the monosity of direct and attenuated light beams makes it possible, with known dispersion in one dimension, to more accurately determine the aerosol concentration, to take into account the measurement error due to multiple light scattering;

The counting concentration is determined by the formula

fls

M)

0

N

(ACP). e with EP (05/36) 62.5, where 35 3 are the currents of the photodetectors 5 and 6 (in the absence of

5 light attenuation of aeroolem 5-3b); a) efficiency factor

light attenuation by the aerool layer depends on

0, the material and the average particle radius - .a are preliminarily determined from the indicative pattern of light scattering;

5 - - thickness of the translucent aerosol layer. It is also possible to determine the volume concentration of particles, the cross-sectional area of the particles, and other parameters from N i spir.

0

The use of the invention allows to improve the measurement accuracy, to improve the condition of setting up and operating the device, to reduce the measurement time.

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Otra: kakaye noSeft) (HOCfnu

GU

Claims (1)

AEROSOL DISPERSION AND CONCENTRATION DEVICE, comprising a collimated light beam source, a measuring volume, a viewing unit of light scattered by an aerosol, mounted with the possibility of angular movement relative to the collimated light beam, polaroids, light filters, a photodetector located on the path of the collimated light beam, with adjustable brightness and a photodetector located in the site of sight, characterized in that, in order to increase the accuracy of measurements in an extended range aerosol concentrations and dispersion, a screen with adjustable brightness and a photodetector are located along the optical axis perpendicular to the axis of the sighting unit, and a reflector with two reflective surfaces and slots used to form comparison fields.