| China is the country with the maximal coal yield and consumption. Particulate matter is one of the main sources of atmospheric particulate pollutants in China.33 percents of total suspended particles in the air are generated by coal fired, including 35 percents submicron particles, which are hazard to the atmospheric environment and people's health. Urgent to control the submicron particles has aroused a world-wide attention. China will gradually raise the standard of coal-fired power plant dust concentration to 50mg/Nm3. The key to achieve that goal is the control of submicron particles. However, submicron particles are too small for electrostatic precipitators to remove. It is necessary that we should find an effective way to deal with submicron particles and improve the traditional precipitators.Physical or chemical agglomerations of submicron particles can make the size of particles big enough to be removed by traditional precipitators, which will increase the separation efficiency of submicron particles effectively. The technology of submicron particle agglomeration will be one of the trends on flue gas dust removal in the future. A method of submicron particles agglomeration enhanced by charged droplets was presented in this thesis Experimental systems were designed and built. Then studies were taken which focus on submicron particles agglomeration enhanced by charged droplets. At last the application project and feasibility analysis on droplets charged technology applied to traditional precipitators were presented.Firstly, electrostatic characteristics of droplets were investigated under negative induction charged. Impacts of factors including voltages, diameters of induction ring, distances from electrode to nozzle and widths of induction ring were investigated and analyzed in this paper. Parameters of droplets charged effectively were obtained. Afterwards, the impact of atomization parameters such as atomization pressures, flow rates and liquid properties was discussed. All the work led to the condition under which droplets better charged. Secondly, the impact of droplets inductively charged to atomization characteristics was studied. Taking the size distribution of droplets and the spray angel as characterizations, the size distribution of droplets and spray angle under different voltages, widths of induction ring and atomization pressures were investigated. Meanwhile, the attraction between high potential electrode and oppositely charged droplets, which was found out in the experiment, was also studied comprehensively. On that basis, the relationship between Electrostatic characteristics and atomization characteristics was discussed. Then the applicable parameters of charging and atomizing were obtained.Finally, at the basis of numerical simulation study on flow field and tracks of charged droplets, pilot experimental system was designed and built. The experimental study on submicron particles agglomeration enhanced by charged droplets was investigated at the exhaust temperature of coal-fired power plant under applicable conditions of charging and atomizing. The result showed that the agglomeration of submicron particles still could be effectively enhanced by water droplets inductive charged at the temperature 135℃. Combining research results and theoretical analysis, this thesis presented the application project and feasibility analysis on the technology of submicron particle agglomeration enhanced by charged droplets. |
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