Degradation in Supercritical Water Oxidation Systems

Supercritical water oxidation (SCWO) can effectively destroy various civilian and military wastes; however, the system will generally need to withstand a corrosive environment To improve our understanding of degradation within such systems, exposure testing is being carried out in conjunction with analysis of failed components. Various alloys have been exposed to environments ranging from deionized water to highly chlorinated organic compounds and to temperatures as high as 600°C. Although, not surprisingly, high corrosion rates are encountered for the chlorinated feed streams, even deionized water can be aggressive at these conditions. In chlorinated feed streams, Hastelloy C-276 exhibits premature failure at subcritical conditions as a result of dealloying and cracking. At supercritical conditions (600°C) in chlorinated environments, both high-nickel alloys and stainless steel exhibited significant corrosion. Analysis suggests that it may be possible to alter feed characteristics to reduce degradation to an acceptable level. This may permit the use of less costly materials for construction