Evaluating stress corrosion and corrosion aspects in supercritical water oxidation systems for the destruction of hazardous waste

Conference · Fri Aug 01 04:00:00 EDT 1997

OSTI ID:509461

Mitton, D B; Zhang, S H; Hautanen, K E; Cline, J A; Han, E H; Latanision, R M ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). H.H. Uhlig Corrosion Lab.

There is, currently, simultaneous public resistance to traditional waste handling procedures and a compelling need to destroy both military and civilian hazardous waste. Supercritical water oxidation (SCWO) is one developing technology particularly appropriate for treating a broad range of dilute aqueous organic wastes. Above its critical point (374 C and 221 atm) water is a low density fluid possessing properties intermediate between those of a liquid and a gas, and solvation characteristics more typical of a low polarity organic than water. Although this is a promising technology, a critical issue in its development will be the ability to overcome severe degradation problems of the materials of construction. While titanium and platinum liners have shown promise for some hazardous military feed streams, costs are high. Although nickel alloys are considered important for severe service, the indication is that they will not survive certain SCWO environments. Nevertheless, there is evidence that judicious feed modification may be employed to mitigate corrosion and reduce fabrication cost. Exposure studies have been accomplished for various alloys over a range of temperatures from 300--600 C. Experiments have been carried out in environments as innocuous as deionized water and as aggressive as highly chlorinated aqueous organic feed streams. Analysis of a number of failed components has provided enlightenment on degradation mechanisms and cracking, pitting and elevated corrosion rates are all observed in these systems. For chlorinated feed streams, both dealloying and cracking have been observed for alloy C-276. Samples exposed to a highly chlorinated organic indicate that the high-nickel alloys behave significantly better at 600 C than stainless steel type 316.

• OSTI ID: 509461
• Report Number(s): CONF-970332--
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
36 MATERIALS SCIENCE
CRACK PROPAGATION
HASTELLOYS
HAZARDOUS MATERIALS
ORGANIC CHLORINE COMPOUNDS
ORGANIC WASTES
STAINLESS STEEL-316
STRESS CORROSION
SUPERCRITICAL GAS EXTRACTION
WASTE PROCESSING PLANTS
WATER VAPOR