Choice of method for determining the concentration and fractional composition of dust and gas flow

Abstract

The presence of industrial dust in concentrations exceeding the MPC leads to environmental pollution and threatens environmental safety. The article presents a method for determining the concentration and fractional composition of the dust and gas flow. The essence of the described method lies in the registration and analysis of vibroacoustic signals that occur due to vibrations of parts of the measuring system. The principle of operation of the system is based on the transmission of shock acts of oscillation generation along a chain that includes dust particles, a boundary layer, a dust pipeline wall, and, finally, a piezoceramic sensor of the system. The disperse composition of dust can be determined by two mathematical models (Fourier polynomials) - one reflects the energy spectrum, the other - the amplitude-phase. These polynomials are obtained by applying the Laplace transform to the signal and actually reveal the physical meaning of the process of formation of harmonics in the frequency subspectra. The processing of an acoustic signal on a computer by a fast discrete Fourier transform leads to an accurate description and calculation of the amplitude-frequency spectrum in real time. The main task is to isolate the frequency subspectra, consisting of the main and timbre harmonics for dust monofractions. The method of static moments is used to refine and form the frequency package of the main harmonics. The implementation of the method is carried out on a laboratory stand during the transfer of a dust-gas flow with pure monofractions and with a stepwise increase in concentration, the amplitudes of the main and timbre harmonics increase, which forms the frequency subspectrum of the analyzed dust monofraction. For further analysis and processing of AS spectra, a block diagram of an algorithm for determining the fractional composition of a moving dust and gas flow has been developed.