以介電質放電法去除502及NO之可行性研究

Abstract

Concern over acid deposition has reulted in more stringent SO2 and NO emission standards as designated by the 1990 Clean Air Act Amendments. In view of the more stringent emission standards and the constraints of current air pollution control technology for removing SO2 and NO from gas streams, more effective air pollution control technologies should be searched. An innovative gas phase oxidation method using dielectric barrier discharges (DBDs ) has been developed to simultaneously remove SO2 and NO from gas streams. This process generates gas phase radicals such as OH, 1102, and 0. The radicals can then oxidize gaseous SO2 and NO to form particles consisting of I-12S04 and 11N03, respectively. The resulting compounds can then be chemically neutralized with NH3 and removed from the gas stream by othe conventional air pollution control devices. The effectiveness of DBDs to remove SO2 and NO from gas streams has been evaluated with a laboratory- scale reactor. Experimental results showed that about 35 % of SO2 can be removed from the gas stream at 160 ℃ with DBDs. This removal efficiency was achieved for a gas stream with an inlet SO2 concentration of 1000 ppmv, H20 concentration of 15 % by volume, CO2 concentration of 12 % by volume, O2 concentration of 6 % by volume with N2 as the carrier gas. The gas residence time is 5 sec and processing voltage is 25 kv (peak value). 99 % removal efficiency for NO was also achieved for the gas stream with an inlet NO concentration of 250 ppmv at the same operating conditions described above. These results indicated that DBDs have the potential to simultaneously remove SO2 and NO from gas streams generated by large scale sources of SO2 and NO, such as a coal-fired power plant. 大眾對酸性沉降之關切已導致世界各國對SO2及NO之排放，採取更嚴格之標準。鑑於目前各種控制方法之限制，有必要研究更有效之控制技術以因應未來之需要。本研究旨在探討利用介電質放電法以同時自氣流中去除SO2及NO之可行性。其過程是藉介電質放電產生OH、HO2及O等自由基利用氣態氧化原理將氣體中之SO2及NO氧化成硫酸與硝酸再移除之，亦可加入NH3中和後再去除。實驗結果顯示，氣流之溫度為160℃時，SO2之去除效率為35%，而NO之去除效率可達99%，此去除效率受使用電壓，氣流成份及溫度、氣體停留時間等操作參數之影響。此研究顯示，未來以介電質放電法同時去除氣流之SO2及NO甚具潛力