The Study Of Dust Concentration Measurement Using Light Scattering

Dust emissions cause air pollution, which poses a threat to the environment and the life. So it is desirable to develop the monitoring technology of dust emissions for protecting the environment. Up to date, most monitoring technologies, which have different defects, are restricted in engineering applications. Light scattering, as a kind of high precision and non-invasive real-time online measurement method, is developing very rapidly. In this paper, a monitoring technology based on light scattering, which is independent on dust size, is proved feasible, and its measurement accuracy, error sources, measurement range are studied in details.At first, the light scattering theory is introduced and the similarity between Mie theory and Fraunhofer theory is proved. On this basis, Scattering Integral Method is derived, regardless of particle size. According to spatial filtering, focusing and alignment of Gaussian beam, optical measurement system based on light scattering for particle concentration is introduced and how to select of optical components are also discussed.The dust concentration measurement error by light scattering system is analyzed using numerical simulations. The influences of dust size, refractive index and the valid range of scattering angle on measurement errors are studied.Parameters of the measurement system are calibrated through pinholes, and its linear dynamic range is tested and verified. The concentration measurement experiments prove the feasibility of measurement system. At last, the lower limit of concentration range and its influencing factors are explored through experiments.