PM2.5 Online Monitoring System Based On Weighing By Electronic Balance

The pollutions of the atmospheric environment problems are increasingly given more prominence so that atmospheric particulates becomes a hot and typical example in research area with the rapid pace of development in industry and social economy. Among them, PM2.5 has been a hot spot on account of its wide sources, heavy influences on environment and human body. In view of the serious situation of PM2.5 pollution, an effective control and treatment plan is urgently demanded. However, an accurate environmental monitoring is the precondition of a scientific recovery. The results produced by major methods of PM2.5 monitoring-β-ray absorption method and oscillation balance method- are greatly influenced by humidity therefore some extent of deviation exists between monitoring results and actual situation. Yet, traditional offline weighing method widely used in China is not able to meet the needs of modern society, for its instantaneity and accuracy defects. Aiming at these defects, this article designs a new PM2.5 online monitoring system based on electronic balance, which adopts cascade impact air sampler cutter, gas exchange dehumidifying thermostat method, automatic sampling filter and electronic balance system, and realizes continuous sampling and automatic measuring.A PM2.5 online monitoring system is proposed in this article based on filter membrane successive sampling, weighing by electronic balance, enabling the traditional method to be applied in online monitoring. According to impact sampling principle and the combination of Stokes kinetic equation and Michaud’s cascade sampling cutter design method, main parameters of sampling cutter are acquired. While sampling radius are 10.6μm and 2.5μm, the aperture, numbers of spray nozzle, the diameter of spray nozzle clusters, length of spray nozzle, and impact distance are 3 mm, 30, 21 mm, 5 mm, 3 mm and 1 mm, 49, 21 mm, 5 mm, 3mm respectively. Then an overall structure of the program is proposed. The good performance of TPU polymer film in moisture-penetrability is taken advantage of, then an NC dehumidification thermostat system is given, which adopts gas exchange dehumidifying thermostat principle. And an experiment is designed to analyze the influencing factors of dehumidification thermostat system such as the remaining time of sample gases, the proportion of dry gas and sample gas, which optimizes the running parameters. the longer time the sample gas stayed in dehumidification thermostat system, the greater the amount of dehumidification was, and the max dehumidification appeared when the residence time was 27s; the flow ratio dry gas and the sample gas has a significant impact on the sample gas dehumidification, and flow ratio increased to 1.17 from 0.5, the dehumidification rate raised correspondingly with the flow rate ratio, what’s more, dehumidification reached a maximum of 50.97% with the flow rate ratio of 1.17, while dehumidifying gradually reduced with the flow ratio increased from 1.33 to 2.0; optimization study showed that time that sample gas stays in the dehumidification thermostat system can be set as 27 s and the flow ratio dry gas and the sample can be set as less than 1.17, in which the sample gas with the max humidity 63.79 g/m3 can be treated successfully. According to standard weighing method, design of the sampling weighing system is completed, which utilizes tray carrying filter folder to finish the switch between sampling and weighing of PM2.5.A PM2.5 online monitoring system based on electronic balance is designed in this article, by discussing the feasibility of the principle, designing and processing of key subsystems, controlling research of influencing systems, and optimizing parameters. Automation is expected to realize in weighing method to monitor PM2.5, which laid a solid foundation of a PM2.5 online monitoring system with our own country independent intellectual property rights...