Basic study on the effect of heavy metal salts on molten salt corrosion

Abstract

In order to improve power generation efficiency, it is required to raise the boiler steam temperature in municipal refuse incinerators to higher temperature and pressure. With such an increase in the temperature of the steam, there is concern that the components in the ash adhering to the surface of the superheater tube may increase hot corrosion. That is, a severe corrosive environment is created by shifting from a temperature at which ash does not melt to a temperature at which ash melts. Since chloride has a lower melting point than sulfate, it is a main cause of molten salt corrosion. In addition, it has been reported that when a sulfate is mixed with a chloride, a eutectic salt is formed and the melting point is remarkably lowered to cause severe corrosion. However, the influence of the mixing ratio of chloride and sulfate and the corrosiveness of ash containing heavy metal salts are not always clear.

Therefore, in this study, ash with different S/Cl ratio was prepared and its corrosion behavior was investigated. Furthermore, ash added with PbCl2 or ZnCl2 as heavy metal salt was prepared and its corrosion behavior was investigated.