Near and supercritical water. Part II: Oxidative processes

This paper is a review of applications of near and supercritical water with a focus on supercritical water oxidation (SCWO). Hydrolytic and hydrothermal reactions have been reviewed in Part I [G. Brunner, Near critical and supercritical water. Part I. Hydrolytic and hydrothermal processes, J. Supercrit. Fluids, this issue]. The potential lies in the complete destruction of persistent, anthropogenic waste material. The obstacles in the technical application are due to the highly corrosive reaction medium and the precipitation of salts. Reactor construction is the decisive feature for a commercial process. First, tank type reactors had been favored. Corrosion was kept low by ceramic material and salt deposition was avoided by a stream of cold and clean water at the reactor vessel walls. Later, tubular reactor design was preferred, and several means to prevent corrosion and salt deposits have been applied.