Design And Application Research Of Atmospheric Particulate Matter Concentration Measuring Instrument

In recent years,haze weather has shown explosive growth in most areas of our country,affecting people’s production and life,and endangering human health.As a result,the problem of atmospheric pollution has become the focus of the whole society.The main air pollutants in haze are particulate matter,including total suspended particulate matter（TSP）,inhalable particulate matter（PM10）and fine particulate matter（PM2.5 and PM1）.This topic is based on the current research significance of particle measuring instruments to use light scattering method to measure the particle concentration in real time.This method is based on the Mie scattering theory,and through the derivation and analysis of scattered light intensity and luminous flux,a single spherical shape is established The relationship between the scattered light intensity of the particles and the particle size,and the standard spherical particles as the basic model,through the relevant simulation calculation of the spherical particles,to obtain the particle mass concentration.The overall plan of the particle measuring instrument based on the light scattering method has been designed accordingly.The main sub-modules in the system including the lighting system,scattered light collection system,gas circuit system,signal acquisition circuit,signal processing system and other related analysis,Design and build to achieve the measurement of particle concentration.Using the calibration system,through the direct voltage signal acquisition method and the system channel number acquisition method,the particle size voltage calibration of 2.5μm and10μm particles is realized.And using Arizona A dust as the particulate matter to be measured to calibrate the relevant parameters and values of the system,so as to obtain accurate solutions ofα=.0865andk_s=.0569×10^-5.To verify the accuracy of the instrument measurement by comparing the measurement of different dust particles with the standard instrument.The results show that the instrument has a good correlation in particle measurement.The value of Adj.R-square can reach above 0.95,and the value of Pearson’r can reach above 0.98.And in the measurement of dust particles with different concentrations,the relative difference between the Adj.R-Square and the Pearson’r is less than 0.003.This also illustrates the accuracy of particle size division and calibration parameter calibration from the side.Application of measuring instruments to the actual site,including the measurement of PM2.5 and PM10 as a particulate matter measurement module in the micro air station,and the measurement of particulate matter in the dust and noise on-line monitoring system.Using the reference method to compare the measuring instruments and test the parallelism of multiple instruments.And perform linear regression analysis and parallel calculation of the test results.The results show that in different places,the correlation coefficient of the data obtained by the two measurements is greater than 0.93 and the parallelism between the instruments is less than 10%,meet the national requirements for the automatic monitoring system of suspended particles.Relatively speaking,the correlation between the measurement results of particulate matter in the atmosphere is significantly better than the results measured in the road dust.This shows that when the concentration of particles is high,the scattering of cluster particles is obvious.At the same time,the temperature,pressure,humidity and other factors in the measurement environment also affect the measurement results.so the stability of the measurement instrument needs to be further improved.