A porous reactor for supercritical water oxidation : Experimental results on salty compounds and corrosive solvents oxidation

Supercritical water oxidation (SCWO) development is limited by corrosion and salt precipitation. Transpiring wall reactors are emerging to cope with these problems. A reactor has been developed in which the inner porous shell is composed of pure α-alumina, to handle organic effluents generated by nuclear activities. The reactor was not proven to be efficient enough to oxidize salty effluents. However, experimental results concerning the oxidation of a mixture of dodecane and tributyl phosphate, which is used as a model effluent, confirmed the ability of the reactor to treat corrosive wastes. High destruction rates were actually achieved (>98%). Phosphorus was totally recovered in the aqueous effluent as phosphoric acid. No corrosion was noticed in the reactor, except upstream from the waste injector. As expected, the inner alumina tube shielded the pressure vessel from corrosion. The assumed sensibility of alumina to thermal gradients was not a limiting factor of the reactor operation.