| The development of social economy has brought the atmospheric particulate matter pollution which can’t be neglected,especially in beijing-tianjin-hebei region.The important project on beautiful Tianjin makes fresh air action one of the key contents to catch a high attention of the atmospheric particulate matter pollution.Fugitive dust pollution is an important source of atmospheric particulate pollution,so online monitoring of fugitive dust pollution is of great significance for the control of atmospheric particulate pollution.Fugitive dust on-line monitoring system is designed in this paper,and combined with the characteristics of the fugitive dust,the open space fugitive dust particle concentration calculation method and measuring system is exploited.The main work in the paper includes the following contents:1)The terminal equipment of fugitive dust on-line monitoring system is designed.firstly,the design of the whole system is introduced.secondly,the design of modules in structure and function is discussed in detail including particle measurement,meteorological parameters detection,video monitoring,data acquisition and data transmission.finally,the management platform is present from aspects of real-time display of datas,query of history datas,alarm system and other auxiliary functions.2)The measuring calculation method of particulate matter concentration in open optical path is designed which is suitable for fugitive dust.First of all,according to the characteristics of fugitive dust,shortcomings of the existing measuring methods are analyzed.Physical quantities computing from Mie scattering theory and the influence of each parameter to light scattering is studied.On the basis of that,the calculation method of fugitive dust concentration is designed.There is an improvement scheme in the problem of the initial value selection and the low-speed data process,and the factors are analyzed which influence the calculation of dust particles concentration measurement results.3)The particle concentration measurement system is designed based on the basic principle of calculation method.From the aspects of light path structure of measurement system,this paper introduces the implementation method of the open measuring with long optical path and the key optical components,advances solutions for the path alignment.From the aspects of circuit hardware,there is a kind of design scheme of data acquisition circuit and data processing method given in the paper.4)The feasibility of measuring method is verified through hydrosol experiments of standard dust and smoke dust experiments instead of fugitive dust.Experimental datas show that goodness of fit for the size distribution is 0.962 from measurement results of the particulate matter module to standard dust.And significant correlation in measurement results is showed from the particulate matter module to the standard instrument in smoke dust experiments.the piecewise linear regression equation is used for system calibration,and as results of that,another sets of experiments show that the system measuring relative error is 7.68% and the uncertainty of measurement is 12.83%,which lays a foundation for the field application. |
