2002 Volume 66 Issue 6 Pages 569-575
The demand for the highly efficient utilization of the heat generated by waste pyrolysis gasification and melting process is increasing. However, since this process is still under development, the corrosion behavior and characteristics of superheater tubes are not fully understood. Some field corrosion tests were carried out at the model plant to determine the corrosion rate and to clarify the corrosion mechanism of superheater tubes. Thickness losses after practical operation up to 2839 h were measured along with characterization of ashes deposited on the surface of the tubes. It was found that the corrosion loss of SUS310S increased markedly as the metal temperature rise above 500°C. Cl, S, Na, K and Ca were detected in the corrosion scale, and the deposit begins to melt at 504°C. These results indicate that the accelerated corrosion above 500°C is caused by melting of alkaline metal chlorides and sulfates in the deposit. Also, it was confirmed that alloying elements of Cr and Ni affect to reduce high temperature corrosion caused by molten salt.
