【作者】 李林；

【导师】 董勇；

【作者基本信息】 山东大学 ， 工程热物理， 2011， 硕士

【摘要】 我国是世界上最大的煤炭生产和消费国,燃煤飞灰颗粒是我国大气颗粒污染物的主要来源之一,空气中总悬浮颗粒物的33%由燃煤生成,其中超细颗粒物占35%,对我国的大气环境及居民身体健康造成严重的危害。燃煤超细颗粒物的排放控制,己得到世界各国的普遍重视,我国也逐步将燃煤电厂烟尘排放浓度标准提高到50mg/Nm3,实现这一目标的关键在于对超细颗粒物的控制,但是由于超细颗粒物粒径太小,难以被静电除尘器除去,所以探索一种有效的超细颗粒物脱除方式并对现有的除尘器进行改良,对超细颗粒物的控制十分必要。利用团聚作用使超细颗粒物长大到传统除尘器所能脱除的范围,将会有效提高除尘器对超细颗粒物的脱除效率。基于此,本文提出水雾荷电促进超细颗粒物团聚增效静电除尘的方法,设计并建立了试验系统,进行了水雾荷电促进超细颗粒物团聚的试验研究,给出了水雾荷电增效静电除尘器的方案和可行性分析。首先,采用负电极感应荷电对喷雾雾滴的荷电特性进行了试验研究。对荷电电压、环形电极直径、电极距喷嘴距离和环形电极宽度对雾滴荷电特性的影响进行了分析,进而研究了喷嘴雾化参数包括雾化压力、喷雾量和雾化液体性质等对雾滴荷电特性的影响,最后遴选出了具有较好荷电特性的操作参数。其次,研究了感应荷电条件对喷雾雾化特性的影响。以雾滴粒径分布和喷雾雾化角作为雾化特性的表征,测试分析了不同电压、不同感应环宽度和不同雾化压力下雾滴粒径及其分布的变化以及喷雾雾化角的变化,并对试验过程中的电极吸附雾滴的回吸现象进行了分析,在此基础上探讨了感应荷电条件下雾滴荷电特性和雾化特性的相互关系,给出了合适的荷电参数和雾化参数。最后,在对中试试验系统流动性和带电雾滴在系统中的运动轨迹进行数值模拟后,设计并建立了中试试验系统,利用选取的合适的荷电和雾化的参数,对燃煤电厂排烟温度环境下水雾荷电促进超细颗粒物的团聚作用进行了试验研究,结果表明感应荷电后的水雾在135℃的烟气温度中仍能够有效促进超细颗粒物的团聚。综合研究结果和理论分析,对水雾感应荷电技术的工业应用进行了应用方案的设计和可行性分析。更多还原

【Abstract】 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.更多还原