Research On Continuous Online Monitoring Technology Of Ultra-Low Concentration Dust Based On Laser Forward Scattering Principle

In recent years,although Chinese economic increases quickly(especially in area of industrialization),a series of environmental pollution problems are more and more serious.One of the most concerned problems is smog.Dust emission is the primary cause of smog problem,so dust emission and monitoring get more and more attention.of the whole society.Under such a serious background,The environmental protection agency issued the lasted strict coal-fired power plant flue gas emission standards(GB13223-2011).Some special areas with serious smog problem even required more strict.How to monitoring such low concentration dust is difficult,and environmental monitoring industry faces on a huge challenge.In this paper,discussing the subject of ultra emission dust continuous online monitoring.First of all,introducing the methods of measuring dust concentration and contrasting respective advantages and disadvantages,determining the laser forward scattering principle as the core theory basis and λ=630nm wavelength as the way of scattering light source.Secondly,introducing the scattering theory,concentration inversion principle and how to realize continuous online monitoring under ultra low emissions back ground.Thirdly,designing the mechanical structure of measure system,the sample pretreatment process and the software of control system as well as man-machine operating system.The mechanical structure of measure system is mainly to meet the waterproof,anti-corrosion,highly centralized system,easy to remove the installation requirements.Sample pretreatment process is mainly to meet the constant speed sampling flow,gas preheating and heat preservation and so on.Software control system mainly includes how to use PLC(programmable logic controller)controlling system of the sampling/reverse switch,temperature controlling,data transmission,parameter alarm,etc.Man-machine operating system is mainly for the convenience of the scene display and operating the system.Using WinCC flexible 2008(Windows Control Center;Windows Control Center)configuration software compiled a set of system monitoring.Finally,the measure system applied to one of coal-fired power plants of north China,comparing the field measurement data with the bureau system data of environmental protection,completed the commissioning of 168,verified the feasibility of the system,the stability and accuracy.