| Summary: | 碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 98 === The total mass collection efficiency of modern well-designed ESP can be as high as 99 %. But for submicron particles its, collection efficiency may be much lower. Such particles emitted into the atmosphere may cause environmental pollution. Therefore, it is necessary to improve the collection efficiency of ESP for submicron particles. In an alternating electric field, different velocity and amplitude of the particles result in collisions. The particles collided with each other result in the small particle grown large one. The large particles are easily removed by electrostatic precipitator.
A combination of electrostatic agglomerate device and ESP was set up in this study. The objectives of this researched include studying the agglomerate characteristics, collection efficiency and ozone concentration of ESP by using alternating electric field.
The experimental results indicated that count median diameter, count mean diameter and geometric mean diameter increased as increasing voltage, decreasing frequency of alternating electric field, and increasing the length of agglomerator. When applied voltage was 16 kV and the frequency was 30 Hz, the submicron agglomeration efficiency was 9.84% and 11.39% for 4.5 and 7 seconds of residence time, respectively. When applied voltage raised from 8 kV to 16 kV, the submicron penetration through the ESP reduced from about 24.12% to 5.50% at frequency 30 Hz and residence time 7 seconds. These results showed that a significant reduction in submicron particle emissions after the electrostatic agglomerator applied.
The ozone concentration was about 140 ppb mainly resulted from the operation of charger. Besides, the particle charge was calculated by using Deutsch-Anderson Equation and terminal electrostatic velocity equation. The particle charge increased exponentially with increasing particle diameter. When the particle size was less than 50nm, the average particle charge was less than unit electron charge because some did not get charge.
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