Open Source Class Atmosphere Fine Particle Emission Characteristics And Control Technology Research

Fine particulate matter of air,which have become the main pollutants of many medium-sized and large cities in China, is seriously harmful to environment and human health.Sources of them are widely distributed and mainly divided into stationary source, open source and mobile source according to their different contribution rates to air. Take the city of Jinan for example, the concentration of respirable particulate matter(RPM) of air beyond the corresponding requirements of ambient air quality standard(GB3095-1996). Open-sources materials,which takes 40-80% contents in the RPM(converse 49.1% of air pollutants),is the main source of RPM of air pollutants.Open-sources materials with its characteristics of uncertain source strength, various discharge location and random emission is classified for a compound-source one. It owns different composition with different urban industrial distribution energy structure, geographical location, weather conditions and terrain conditions. Therefore, it is necessary to understand the fine particle emission characteristics of the open source. Becauseit not only has theoretical significance for improving the urban living environment and controlling pollution in air,but also has important practical significance for the full implementation of the sustainable development strategy and achievement of national pollutants emissions planning objectives in the next five years.Previous studies have focused on fine particles (RPM) of the basic physical and chemical properties, toxicological properties and sources of fine particles,but few research about the producing mechanism of fine particles for urban open-sources materials and the domestic research were always follow the foreign results and just remain in the adaptation of the level of research. In addition the domestic research have mainly focused on the laws, and organized fine particles especially for the release of large fixed sources of fine particles which were produced by power steel, mining and other industries but less focused on the release of urban fine particle pollutants of open source.In this experiment, four kinds of open-sources materials as subjects(construction dust, road dust, the yellow river sand, ground dust)were selected. Computer measurement and control platform with powder material free-falling dust overflow experimental methods were used to research the fine particulate matter emission in free-fall process under online humidifying condition of open-sources materials. Under certain dynamic conditions(horizontal wind speed), the relationship between rate of the emission and water flow, nozzle pressure type of material, size distribution, moisture content, mass flow had been discussed.As the results shows, there exsits exponential relationship between emission rate and free-falling material mass flow, moisture content. With increasing of mass flow and moisture content, the rate of fine particle emissions rate decreased, and the reducing speed gradually slows down. Fine particle size is the most important factor which can affect its emission rate and their exsits a exponential function relationship between them. Different materials can also affect the emission rate of fine particle size. In this experiment, ground dust discharged the most RPM but with the least emission rate and the yellow river sands discharged the least but with the most emission rate. The higher the moisture content of samples have,the lower fine particle emissions rate have, but it is not applicable to the situation above when moisture content is beyond 1.34%, physical properties of materials will change significantly. Humidification is a simple and effective method to reduce the fine particle emissions rate of free-fall materials.When Online humidification were used, the particle emissions rate are different with the different air pressure of atomizing nozzle and water flow. When gas-water two-phase nozzle is used and the air pressure is 0.3MPa, fine particle emissions rate have minimum function value. When the water flow rate is 40mL/min, the fine particulate emissions rate is the lowest.In this paper, the rate of emission of fine particulate in the free-fall process of open-sources materials under uncertain dynamic conditions was studied. The mathematical model had been established between the rate of fine emission and water flow, nozzle pressure type of material, size distribution, moisture content, mass flow. Then the models were modified by SigmaPlot mathematical analysis software.It was found that the fine particle size is the most important factor which can affect its emission rate in the materials free-fall process. The operating conditions of water line was optimized. It can provide a reference by the results for making source control programs of fine particles and selection of technical measures to control open-sources fine particle emissions.