Research On Measuring System Of Multi-particle Dust Mass Concentration

Effective dust detection is needed to study the dust pollution’s nature and distribution pattern since that it is becoming a global problem,due to the rapid development of industry and manufacturing.In this paper,we have developed a dust concentration measurement system using a combination of photometric and single-particle scattering methods to improve the accuracy of the photometric method in a multi-particle dust environment,in response to the problem of low measurement results due to the presence of large particles when using the existing photometric method at home and abroad.Based on the Mieplot and Fronhofer diffraction theories,this paper deduces the relationship between the scattered light flux of particles and mass concentration,and concludes that the light flux of particles becomes a monotonic function of mass concentration when the distribution characteristics of the particles to be measured remain unchanged,and establishes a model for the measurement of mass concentration of multi-particle size dust.The light harvesting method and collection angle of the prototype sensor were determined by using Mieplot and Matlab to simulate the factors affecting the light intensity distribution of particles such as particle size,incident light wavelength,particle extinction coefficient and light harvesting collection angle.The F-D curves of the particles are simulated in combination with the light harvesting method,and according to the nonlinearity of the curves in different particle size intervals,the idea of segmental fitting of the curves is proposed to reduce the errors caused by the nonlinearity of the overall fitting.The design of the sensor housing and circuit system is completed based on theoretical calculation and simulation analysis,and the existing diaphragm is optimized to improve the signal-to-noise ratio of the system.Finally,the dust measurement system was experimentally verified and the calibration of the concentration conversion factor K value was completed.By comparing the results with the standard device 8533 dust concentration meter from TSI,it was determined that the sensor had an error of about 5%in the range of 0-10 mg/m~3 and 10%in the range of 0-20 mg/m~3,which reached the standard set by JJG846-2015"Dust Concentration Measuring Instrument Calibration Regulations".