Design of an Atmospheric Non-Thermal Plasma VOC Elimination System

• Main Authors: Chao Hsin Yuan, 袁兆新
• Other Authors: K. H. Hou
• Format: Others
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/32147057943215286073

碩士 === 長庚大學 === 機械工程研究所 === 97 === Volatile Organic Compounds (VOCs) may result in serious damage to human body via direct contact or breathing. These compounds will also form ozone in the smog by various photochemical reactions. Although most of VOC pollution can be effectively controlled to some extent nowadays, there is still plenty of room for improvement. The major techniques used in this study to eliminate VOC include (1) using multi-layer fibrous activated carbon to absorb VOC; (2) using a desorption electrode unit to form non-thermal plasma to release and decompose the VOC molecules which are absorbed by the fibrous activated carbon; and (3) using a decomposition electrode unit to form non-thermal plasma to decompose VOC of various concentrations directly. In this study, a high-frequency, high-voltage pulsed power supply was used for both the desorbing electrode unit and the decomposing electrode unit. A plasma-based pollution eliminating system will be composed of several working modules, which consist of a adsorption/desorption electrode unit and a decomposition electrode unit. In this study, gaseous acetone was used as the source of VOC. The acetone concentrations were between 50 ppm and 5000 ppm and the flow is between 1 L/min and 5 L/min. Experimental parameters include desorption and decomposition currents, distance between electrodes, and speed of desorption electrode scan. It was observed that the moving absorption/desorption electrode unit not only was able to revive fibrous activated carbon but also to decompose significant amount of acetone molecules at same time. Experimental results indicate that the mobile adsorption/desorption electrode revive fibrous activated carbon and decompose mass acetone at same time. The efficiencies of using decomposition electrode only to decompose acetone of 5000 ppm and 500 ppm in concentration and the flow rate in 1L/min are 87% and 91.5％, respectively. When the concentration of acetone is 5000 ppm, using 4 decomposition electrodes in series can reduce the acetone concentration to under 10 ppm. The combined effect of the adsorption/desorption electrode unit and the decomposition electrode unit in a single-module pollution eliminating system can consistently reduce an acetone gas of 1000 ppm to lower than 47 ppm when the power supply is continuously functioning for both electrode units. In order to reduce energy consumption, an elimination system made of 2x3 modules was designed and the efficiency achieved 90% or higher consistenetly. In this research, the best decomposition efficiency and best energy efficiency of the elimination system were also discussed and suggested.