- 學位論文
以微波反應活性碳循環床處理NOx之研究
A Study of Nitrogen Oxides treatment by Activated Carbon in a Circulating Fluidized-Bed with Microwave system
摘要
氮氧化物是造成酸雨和光化學煙霧的重要前趨物之一，控制氮氧化物排放量的方法可分為燃燒控制與後燃燒控制，但是在很多情況下，燃燒控制並不能很有效的達到所要求的標準，所以需以後燃燒控制法來處理氮氧化物。其中又以選擇性觸媒還原法較為普遍，但是其在還原過程中還原劑的溢散、腐蝕等問題還有待解決，所以再找尋更合適的技術是刻不容緩的事，因此如何有效降低氮氧化物之排放，對產業界乃是一項挑戰。 本研究使用微波技術再生活性碳，乃因微波具有較高之能源使用效率及較高穿透性，不僅可提高吸附質之脫附效率，亦可節省大量能源之損耗。利用微波能源來處理氮氧化物，其過程藉著活性碳為介質吸附氮氧化物，藉由微波的誘導作用，於活性碳間產生蒸汽蒸餾作用及弧光作用而使氮氧化物裂解還原為一氧化碳、氮氣和二氧化碳最終產物，並同時自活性碳脫附排出。 微波技術不僅可以應用於氮氧化物之吸附及處理，同時又可達到活性碳再生，使活性碳重複使用之功效，相當符合資源再利用的環保理念，亦提供了另一種處理技術上的選擇性。此方法與傳統方法相比，可以避免傳統方法的氧化産物對設備腐蝕性強、處理程序複雜、處理成本較高等缺點。 經實驗結果顯示，使用微波功率450W處理NO、NO2濃度200 ppm，其處理效率可達到八成左右；以550 W微波功率操作時，其處理效率更可達八成以上。以NO 200 ppm混合NO2 100 ppm、微波功率550 W其去除效率也將近達到八成。利用微波加熱反應活性碳，其結果顯示活性碳表面溫度隨微波輸出功率增加而上升，以微波輸出功率550W而言，加熱15分鐘後溫度可達到穩定狀態約350℃，且加熱溫度持續平穩至30分鐘以上。經微波檢測器檢測微波爐周圍之洩漏量，發現微波可被一般的金屬網所隔離，可使周圍之洩漏值降到安全值以內。
並列摘要
Nitrogen oxides (NOX) are important precursors of acid rain and photochemical smog. Combustion controls and post-combustion controls are the two main categories for NOx emission reduction techniques. However, combustion controls along are not effective enough to achieve the regulation requirement in most cases. Therefore, adaptation of post-combustion controls to remove NOx from the exhausted stream is usually needed. Amongst all the pos-combustion techniques, SCR method is one of the common practices. Yet, during the process of most SCR method, the corrosive reductants can lead to further pollution. As a result, developing alternative control technology is of the highest priority to effectively reduce NOx emission for the industry. This research used activated carbon to absorb NOx, and employed microwave technology to regenerate activated carbon. Because microwave has higher energy efficiency and penetration, and then enhances the desorption efficiency. Through the induction of microwave, the steam distillation and arcing effects inside activated carbon can pyrolyze NOx to N2, CO, and CO2. Microwave technology applied to nitrogen oxide treatment may avoid the disadvantages of traditional methods, such as equipment corrosiveness, complicated disposal procedure, and high operational cost. Microwave power 350, 450, and 550 W were applied to treat NOx at hundreds ppm concentrations. The results showed that the treatment efficiency of NO, NO2, and mixed NOx could reach above 80%. Temperature of the activated carbon rose gradually and reached to approximately 350 ℃ after 15 minutes heating under microwave power output as 550W. The higher microwave power output, the higher activated carbon temperature was.