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

摘要

The influence of H2S Concentration (CH2S) and SO2 concentration (CSO2) to thecorrosion behavior and the dependence of oxygen partial pressure (PO2) and sulfur partialpressure (PS2) that were estimated from the gas composition using thermodynamic calculationto the corrosion behavior were investigated in the simulated coal combustion gases at 773Kfor 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 inthis study could be classified into three regions according to the dependence which eachfactor gave to corrosion behavior.Region Ⅰ (low PO2 and high PS2 condition): In this region, although corrosion amountbecame large, corrosion amount of STBA24 was steady even if PO2 and PS2 change. While, itwas clarified that the corrosion amount were susceptible to the influence of either CH2S orCSO2 change. Therefore, it was concluded that corrosion amount could be evaluated by eitherCH2S 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 changeinfluenced corrosion amount as well as PO2 and PS2 change because this region seemed to betransition region between regionⅠ to region Ⅲ.Region Ⅲ (high PO2 and low PS2 condition): In this region which corrosion amount becamesmall, corrosion amount of STBA24 increase or decrease according to PO2 and PS2 change. Onthe other hand, the corrosion amount was steady when CH2S and CSO2 changed at same PO2and PS2. Therefore, it was concluded that corrosion amount could be evaluated only by thecorrelation of PO2 and PS2 in this region.