應用碳氣化方法於零價鐵流體化床處理燃燒廢氣中一氧化氮之研究

Using Carbon Gasification for Nitrogen Monoxide Removal from Flue Gas by Zero Valent Iron Fluidized Bed

許文熙(Wen-Shi Shiu)

指導教授 ： 陳孝行

國立臺北科技大學/工程學院/環境規劃與管理研究所/碩士(2007年)

摘要

本研究係以零價鐵粉及活性碳粉之流體化床管柱定溫反應穿透實驗，探討不同反應溫度、進流濃度、流通量、鐵粉/碳粉量及模擬不同含氧濃度下之燃燒廢氣等影響因子，對在零價鐵流體化床中碳氣化所產生CO與去除煙氣中NO之影響性；並求得流體化床於不同反應溫度之單位鐵粉NO去除量；同時透過實驗反應後零價鐵之XRD試驗，確認其可能反應產物，並探討其可能反應機制。
從溫度效應方面，在NO進流濃度為240 ppm，鐵粉量為0.5 g，碳粉量為0.5 g，流通量為0.3 L/cm2•min時，反應溫度573 K的NO去除率幾乎無效用。在623 K時，NO在500~7000秒的平均去除率39.7%，O2的平均利用率12%。於673K、723 K、773 K時，在[NO]=50ppmv的穿透點位置時，單位鐵粉去除能力分別為1.56 mg NO/g Fe，6.53 mg NO/g Fe，7.89 mg NO/g Fe；另外，在[NO]=75ppmv的穿透點位置時，單位鐵粉去除能力分別為6.24 mg NO/g Fe， 7.63 mg NO/g Fe，8.63 mg NO/g Fe。顯示在此溫度範圍下，單位鐵粉去除NO的能力隨著反應溫度上升NO去除率亦增加。
在進流濃度效應，對於NO進流濃度240ppm的變化至少有三倍的涵容能力，不會損失的原有的去除能力。在0.6、0.7、0.8 L/cm2．min不同流通量的NO穿透時間均隨流通量增加而降低，兩者呈線性關係。NO穿透時間會明顯受碳粉量所影響，當採取鐵粉量固定而碳粉量增加時則與NO穿透時間呈現線性正相關，其單位鐵粉處理NO能力亦隨碳粉量增加而成比例增加。煙氣中含氧濃度對NO還原有影響，即當煙氣中含氧濃度升高對處理NO能力明顯下降。
在高溫低氧環境下，固體碳因熱解氣化而持續提供還原性氣體CO，且零價鐵能併同處理NO、CO，使氧化程序及還原程序同時發生，讓NO穿透時間與碳粉量增加而延長處理效果，且NO去除量均較僅行還原程序的零價鐵單獨處理NO效果佳；使用過鐵粉量經XRD試驗結果，其主要反應產物為C、Fe0(ZVI)、FeO

關鍵字

零價鐵 ； 觸媒 ； 一氧化碳 ； 一氧化氮 ； 流體化床 ； 碳氣化

並列摘要

This research uses fluidized column set reaction temperature of zero valent iron and the active carbon powder, to go pass through the experiment, to probe into different reaction temperature, entrance flow concentration and iron powder / carbon powder quantity. Also, this research stimulates the influential factors such as the flue gas under different oxygen concentration and influential nature towards carbon gasification produced CO and NO in the elimination of exhaust gas; obtains the unit iron powder NO elimination quantity of the fluidized bed at different reaction temperature; Simultaneously, through experimenting the XRD examination discusses its possible reaction mechanism.
In the temperature effect aspect, when [NO] inlet = 240ppmv, Fe=0.5g, C= 0.5g, and flux is 0.3 L/cm2．min, NO removal efficiency of reaction temperature 573K has almost no effect. At 623 K, NO removal efficiency avg.≒39.7% and at about 12% O2 reacted efficiency. At 673K, 723 K, 773 K, when [NO] = 50ppmv breakthrough point, ZVI treatment ability are at 1.56mg NO/g Fe, 6.53 mg NO/g, and 7.89 mg NO/g Fe， when [NO] = 75ppmv breakthrough point, ZVI treatment ability are at 6.24mg NO/g Fe, 7.63 mg NO/g, and 8.63 mg NO/g Fe. It is shown under these temperature ranges, NO removal efficiency and the ZVI treatment ability increases along with the raise of the reaction temperature.
In the entrance flow concentration effect, as to the changes of NO entrance flow concentration 240ppm, there are at least three times the tolerance ability that will not create damages or losses to the existing elimination ability. At 0.6, 0.7, 0.8 L/cm2．min, NO breakthrough time decreases as the flux increases. NO breakthrough time is obviously influenced by the carbon powder quantity. When iron powder quantity is fixed and when the carbon powder quantity increases, they are positively correlated to the NO breakthrough time. Its ZVI treatment ability (as mg NO/g Fe) increases along with the carbon quantity increase in proportion. The flue gas consisting oxygen concentration has influences over NO reduction. The increase in oxygen concentration in the flue gas obviously decreases the NO removal ability.
Under the environment of high-temperature and low oxygen, solid carbon gasified to provide reducing agent CO. Using CO for reduction of NO by ZVI fluidized bed. In these studies, both higher temperature and more carbon weight can achieve higher the capacity of ZVI for De-NO. XRD (X-Ray powder Diffraction) were conducted to analyze the crystal structure and oxidation state of the reacted powders. Several species were determined from the spectrum：C,Fe0(ZVI),FeO•Fe2O3 and Fe3O4.

並列關鍵字

zero valent iron（ZVI） ； nitrogen monoxide (NO) ； carbon monoxide (CO) ； fluidized bed ； carbon gasification

參考文獻

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