A double wall reactor for supercritical water oxidation: Experimental results on corrosive sulfur mustard simulant oxidation

The corrosion of reactor is one of the obstacles that inhibiting the development of supercritical water oxidation (SCWO) into a viable industrial process. A concentric vertical double wall reactor has been developed in which SCWO reaction takes place inside an inner tube (titanium grade 2, non-porous) whereas pressure resistance is ensured by a Hastelloy C-276 external vessel, to handle high-risk wastes resulting from munitions demilitarization. Experimental results concerning the oxidation of a mixture of thiodiglycol [TDG, (HOC2H4)2S] and hydrochloric acid [HCl], which is used as a sulfur mustard stimulant, confirmed the ability of the reactor to treat corrosive wastes. High destruction rates based on total organic carbon were achieved (>99%) without production of chars or undesired gases such as carbon monoxide and methane. The carbon-containing product was carbon dioxide. Sulfur and chloride were totally recovered in the aqueous effluent as sulfuric acid and hydrochloric acid. No corrosion was noticed in the reactor. The titanium tube shielded the pressure vessel from corrosion.