Corrosion resistance of stainless steels in chloride containing supercritical water oxidation system

As the science and process applications of supercritical water (SCW) and su percritical water oxidation (SCWO) become more thoroughly understood, it is logical to envision the use of the SCWO process by diverse industries and public wastewater and sludge generators. This technology can be adapted to accomplish either pre or end-of-pipe wastewater treatment. There is a need to destroy both military and civilian hazardous waste, and urgency, mandate d by public concern over traditional waste handling methodologies, to ident ify safe and efficient alternative technologies. By capitalizing on the pro perties of water above its critical point, 374 degrees C and 22.4 MPa for p ure water, this technology provides rapid and complete oxidation with high destruction efficiencies at typical operating temperatures. Nevertheless, c orrosion of the materials of fabrication is a serious concern. While iron-b ased alloys and nickel-based alloys are generally considered important for service applications, results from laboratory and pilot-scale SCWO systems presently in operation indicate that they will not withstand some aggressiv e feeds. Significant weight loss and localized effects, including stress co rrosion cracking (SCC) and dealloying, are seen in chlorinated environments . This work assesses the corrosion characteristics of iron-based stainless steels exposed to high supercritical temperatures in a chlorinated military waste containing salts.