The Classification of influence that each factor gives to corrosion behavior of STBA24 in the reducing atmosphere including H2S

摘要

The influence of H2S Concentration (CH2S) and SO2 concentration (CSO2) to the corrosion behavior and the dependence of oxygen partial pressure (PO2) and sulfur partial pressure (PS2) that were estimated from the gas composition using thermodynamic calculation to the corrosion behavior were investigated in the simulated coal combustion gases at 773K for STBA24. After corrosion test in the conditions that PO2 and PS2 change at same CH2S and same CSO2, and the conditions that CH2S and CSO2 change at same PO2 and PS2, the test condition range in this study could be classified into three regions according to the dependence which each factor gave to corrosion behavior. Region Ⅰ (low PO2 and high PS2 condition): In this region, although corrosion amount became large, corrosion amount of STBA24 was steady even if PO2 and PS2 change. While, it was clarified that the corrosion amount were susceptible to the influence of either CH2S or CSO2 change. Therefore, it was concluded that corrosion amount could be evaluated by either CH2S or CSO2 without depending on PO2 and PS2 in this region. Region Ⅱ (middle PO2 and middle PS2 condition): in this region, CH2S and CSO2 change influenced corrosion amount as well as PO2 and PS2 change because this region seemed to be transition region between regionⅠ to region Ⅲ. Region Ⅲ (high PO2 and low PS2 condition): In this region which corrosion amount became small, corrosion amount of STBA24 increase or decrease according to PO2 and PS2 change. On the other hand, the corrosion amount was steady when CH2S and CSO2 changed at same PO2 and PS2. Therefore, it was concluded that corrosion amount could be evaluated only by the correlation of PO2 and PS2 in this region.