Enhancing dust concentration monitoring in high particulate matter environments: A dual-light source particulate matter sensor approach based on Mie scattering

Abstract

Accurate real-time monitoring of mine particulate matter is essential for comprehensive dust control in coal mines. Because of the high concentrations of PM10 in mines, when traditional optical dust concentration sensors are used, large dust particles at the front end can prevent the rear dust particles from receiving light signals. Thus, the laser beam is scattered selectively when passing through the dust mass, which decreases the measured concentrations. This paper presents a dual-light source respirable particulate matter concentration sensor based on Mie scattering. A calculation program written in MATLAB analyzed the scattered light intensity distribution at different angles of 0.1–7μm dust particles under 300–900 nm laser irradiation. There was not a one-to-one correspondence between the intensity and particle diameter; larger particles did not always scatter more light at specific angles. Further simulations were conducted to analyze the light intensity distributions of laser beams with different wavelengths after passing through the mass of polydisperse dust particles. The peak scattering intensity was at approximately 488 and 640 nm. Furthermore, an experimental system was constructed to test the dual-wavelength light scattering characteristics of the dust particles. The optimal placement of the light source and photodetector was determined experimentally, and the sensor hardware and software system design were completed. The anti-noise performance results indicate that when the noise was not greater than 5 %, the dust concentration results of the sensor remained sufficiently accurate. The experimental results demonstrated that the sensor performed reliably and accurately for different measurement intervals; the correlation coefficient R of the test data and filter membrane weighing and calibration data was 0.983.