Method for determining dispersed composition of dust

Abstract

FIELD: monitoring air pollution.SUBSTANCE: monitoring air pollution in the work area and the environment. Method for determining the dispersed composition of dust is disclosed, which includes collecting dust samples on an analytical filter, determining the mass of the collected dust using a gravimetric method, obtaining microphotographs with a digital camera, processing them using graphic programs and using the obtained data to determine the parameters of the dispersed composition of dust, wherein the filters are illuminated through a control unit using RGB LEDs in transmitted and reflected light of a different spectrum, microphotographs are taken from the studied filter zones and taking into account the depth of penetration of particles at a selected magnification in the range of 100-200.EFFECT: makes it possible to increase the accuracy and objectivity of studying the fractional composition of dust at high concentrations in the air.1 cl, 4 dwg

Description

[0001] The invention relates to a technique for determining the sizes and shapes of dust particles suspended in gases at various concentrations, and can be used in monitoring air pollution in the work area and the environment.

[0002] A known method for determining the fractional composition of dust using an optical method includes collecting dust samples on an analytical filter, determining the mass of the collected dust using a gravimetric method, preparing samples for microscopic analysis by clearing them with a solvent, obtaining microphotographs and processing them using graphic programs (such as Adobe Photoshop) and analyzing the parameters of the dispersed composition using the special program "SPOTEXPLORER V1.0" (GOST R 56929-2016).

[0003] The disadvantages of the known method are:

[0004] - insufficient objectivity of the study of the fractional composition of dust due to the lack of identification of the studied filter zones, which can lead to errors in determining the parameters of the dispersed composition of dust at high concentrations in the air;

[0005] - reduced accuracy of determining the parameters of the dispersed composition of dust due to the use of organic solvents, microscopy at several magnifications and the lack of consideration of the depth of penetration of particles into the analytical filter, which can lead to the loss of recording of a significant number of particles.

[0006] The objective of the invention is to improve the objectivity of the study of the fractional composition of dust at high concentrations in the air and to improve the accuracy of determining the parameters of the dispersed composition of dust.

[0007] The stated objective is achieved by the fact that the method for determining the dispersed composition of dust, including collecting dust samples on an analytical filter, determining the mass of the collected dust using a gravimetric method, obtaining microphotographs with a digital camera, processing them using graphic programs, obtaining with the help of special programs the number of detected particles, the area and perimeter of the particle image, the roundness coefficient, the maximum linear size, the ratio of the maximum to the minimum size, using the obtained data to determine the parameters of the dispersed composition of dust, unlike the prototype, the enlightenment of the filters is carried out through the control unit using RGB LEDs in transmitted and reflected light of a different spectrum, microphotographs are taken from the studied areas of the filter and taking into account the depth of penetration of particles at a selected single magnification in the range of 100-200.

[0008] The result is that the proposed method for determining the dispersed composition of dust using an optical method will improve the accuracy and objectivity of studying the fractional composition of dust at high concentrations in the air.

[0009] The essence of the invention is explained by the drawings, where Fig. 1 shows a basic diagram of the installation for obtaining digital microphotographs, Fig. 2 is a diagram of the arrangement of the main zones of the analytical filter of radius Rф under study when the number of particles detected on them is more than 1000 pieces, Fig. 3 is a diagram of the arrangement of additional zones of study when the number of particles detected is less than 1000 pieces, Fig. 4 is a diagram (view A) of adjusting the distance between the filter and the microscope objective for detecting particles in the depth of the filter.

[0010] The setup (Fig. 1) for obtaining digital microphotographs consists of a microscope stand 1, elements of the optical system (objective 2, eyepiece tube 3 with digital camera 4), providing a total magnification of 100-200, a Barlow lens 5, a movable stage 6, on which a slide 7 with an analytical filter 8 is placed. The analytical filter 8 is illuminated by RGB LEDs 9 of transmitted light and RGB LEDs 10 of reflected light, which are connected through a control unit 11 to a PC 12.

[0011] The method for determining the dispersed composition of dust using an optical method includes collecting dust on analytical filters 8, determining the mass of the collected dust using a gravimetric method, obtaining microphotographs using an installation (Fig. 1) in the studied zones (Fig. 2 and 3, pos. 13...31) of the analytical filter 8, taking into account the depth H глпрpenetration of particles (Fig. 4), and the different spectrum of transmitted and reflected light created by RGB LEDs 9 and 10 using a PC 12 through a control unit 11, preparing images on a PC 12 in graphic programs such as Adobe Photoshop, Paint, Paint.net, etc. in order to obtain high-contrast images. The prepared images are processed in special programs to obtain the following data: the number of detected particles, the area and perimeter of the particle image, the roundness coefficient, the maximum linear size, the ratio of the maximum to the minimum size. To determine the parameters of the dispersed composition, the obtained data are processed using a spreadsheet program (such as Excel) as follows:

[0012] - calculate the aerodynamic diameter of each detected particle;

[0013] - calculate the decimal logarithm of the maximum linear size or the aerodynamic diameter of each particle;

[0014] - find the mathematical expectation and standard deviation based on the logarithm of the size of the studied particles;

[0015] - raise the values ​​of the aerodynamic diameters of the particles to the third power and find the proportion of each particle in their total mass;

[0016] - plot a cumulative graph of the particle content from the decimal logarithm of the size;

[0017] - determine from the graph the value of the decimal logarithm of the particle size at their share of 50% and the value of the decimal logarithm of the size at their share of 84.1%;

[0018] - from the obtained values, the average particle size and the logarithmic standard deviation of their sizes are determined, which are the parameters of the dispersed composition of dust.

[0019] The values ​​found using the law of logarithmic normal distribution will allow us to obtain data on the content of particles of different fractions and use them in calculations of dust cleaning devices and in assessing the impact of dust on humans in the air of the working area.

Claims

A method for determining the dispersed composition of dust, including collecting dust samples on an analytical filter, determining the mass of the collected dust using a gravimetric method, obtaining microphotographs with a digital camera, processing them using graphic programs, obtaining using the programs the number of detected particles, the area and perimeter of the particle image, the roundness coefficient, the maximum linear size, the ratio of the maximum to the minimum size, using the obtained data to determine the parameters of the dispersed composition of dust, characterized in that the enlightenment of the filters is carried out through a control unit using RGB LEDs in transmitted and reflected light of a different spectrum, microphotographs are taken from the studied areas of the filter and taking into account the depth of penetration of the particles at a selected single magnification in the range of 100-200.

Images