FGD系統中內襯不銹鋼合金的腐蝕行為

Corrosive Behavior of Stainless Steel Alloys in an FGD System

本研究以電化學方法來評估三種不銹鋼合金（317LM、654SMO及254SMO）在FGD系統中做為內襯材料之適用性。實驗採用直流電極化法及交流電阻抗頻譜法，在綠色溶液腐蝕液中評估其耐蝕性。結果顯示：317LM不銹鋼合金在通空氣之綠色溶液環境下其鈍化膜成長最迅速，但其鈍化膜之防蝕效果不佳。相較而言，654SMO及254SMO則表現出良好的耐蝕性，尤其654SMO合金在溫度較高的環境下，鈍化效果依然明顯，其鈍化膜在高溫下仍具良好安定性。在綠色溶液中254SMO合金鈍化膜的成長速率，會隨溫度上升而下降，此鈍化膜會因溫度上升而被破壞。654SMO合金具有最佳之抗蝕性。

Electrochemical techniques were employed to evaluate the corrosion behavior of stainless steels (i.e., 317LM, 654SMO and 254SMO) in an attempt to select proper lining materials used in the flue gas desulfurization (FGD) system of a fossil power plant. A direct current polarization technique and alternating current impedance spectroscopy were conducted in a corrosive medium of green solution to measure the corrosion rate and compare the corrosion resistance of the specimens. The results indicated that it was faster to form a passive film on the surface of 317LM than on those of 654SMO and 254SMO although the corrosion resistance of the film on 317LM was relatively poor. In contrast, 654SMO and 254SMO exhibited higher resistance to corrosion, especially at elevated temperatures where the passive film of 654SMO remained very stable. In the green solution, a passive film tended to grow on 254SMO but the growth rate decreased with increasing temperature. The passive film was subject to degradation at higher temperatures. Among the tested materials, 654SMO showed the best corrosion resistance in the system.