PREDICTION OF CORROSION RATE FOR ALLOYS EXPOSED TO REDUCING SULFIDIZING COMBUSTION GASES/

The presence of reducing/sulfidizing combustion gases in Mle lower fur nace of utility boilers can lead to accelerated corrosion wastage on t he furnace walls. The corrosion has been attributed to the formation o f hydrogen sulfide (H2S) that attacks the furnace walls, primarily via sulfidation. In a previous laboratory study, the corrosion rates of s everal Fe-base alloys were determined as a function of three key indep endent variables (i.e., H2S concentration in the flue gas, Cr concentr ation in the alloy, and metal temperature). The results were used to d efine the trend of corrosion data, regression of the variables individ ually. To better utilize the previous corrosion data,regression analys is was performed to correlate the corrosion rates of these alloys with the three variables simultaneously. From this analysis, simple mathem atical equations were generated that were capable of predicting corros ion rates of Fe-base alloys exposed lo reducing/sulfidizing boiler env ironments. The accuracy of the equations was evaluated by comparing pr edicted and actual corrosion rates of a low-alloy steel from the furna ce wall of a partial combustion-fired utility boiler. A reasonable agr eement was obtained.