Design of a Small-Scale Supercritical Water Oxidation Reactor. Part I: Experimental Performance and Characterization

A small-scale supercritical water oxidation reactor is designed and fabricated to study the destruction of hazardous wastes. The downward bulk flow is heated with the introduction of pilot fuel (ethanol/water mixture), and oxidant (H₂O₂/water mixture). Both streams are introduced coaxially. The fuel dilution is varied from 2 to 7 mol% ethanol/water, and the oxidant-to-fuel stoichiometric equivalence ratio (Φ_AF), is varied from 1.1 to 1.5. Higher ethanol concentrations in the pilot fuel stream and operation near-stoichiometric results in a more stratified temperature profile, i.e., highest local fluid temperatures near the top and the lowest temperatures at the bottom of the reactor. Steady operation at 603.5 °C is achieved with a nominal residence time of 25.3 s at 7 mol% fuel dilution and Φ_AF of 1.1. At the lowest pilot fuel dilution (2 mol%), the temperature profile is nearly uniform, approaching a distributed reaction regime.