Effects of Oxygenated Treatment on Exfoliation of Duplex Scale in Steam Path

Oxygenated treatment (OT) is an excellent choice for supercritical (SC) and ultrasupercritical (USC) fossil units to alleviate flow accelerated corrosion (FAC). Unfortunately, many large utility boilers had suffered series bursts caused by exfoliation of duplex scale in steam path after adopting OT measures. It has been hopeful always about that OT should be independent of scale exfoliation, but many tube failures in fossil power plants go by contraries. Ecocide hypothesis which has been verified reveals the secret of the causal relationship between OT and exfoliation. Ecocide is the abbreviation of “Evaporating Consumption of Chromium Induced Disastrous Exfoliation” and that’s the essence of our hypothesis. We can explain the mechanism of exfoliation of duplex scale in oxygenated steam path with the help of ecocide hypothesis, and furthermore we can predict the risk of OT. Concerned with operating utility boilers which intend to apply OT, the longer the operating history, the greater the risk; the higher the concentration of oxygen in steam, the greater the risk; the higher the parameters of steam, the greater the risk. To avoid the risk of exfoliation, OT should be synchronously scheduled in commissioning.