Experimental Study of the Viability of the Destruction of Different Kinds of Waste by Supercritical Water Oxidation at Hydrothermal Flame Regime

The use of reactors working with a hydrothermal flame as a heat source contributes to overcome many of the challenges presented by supercritical water oxidation (SCWO). Injection of the reagents over a hydrothermal flame can avoid the reagents preheating as the feed can be injected into the reactor at room temperatures, avoiding plugging and corrosion problems in a preheating system. Also the kinetics is much faster allowing complete destructions of the pollutants in residence times lower than seconds. The aim of this work is to check the feasibility of destroying different kinds of waste by using a hydrothermal flame in a new design of cooled wall vessel reactor and check the advantages of this new design compared to other previous reactors designs. The wastes tested were the following: Solutions with IPA concentrations between 9-12% in mass, IPA solutions containing high inorganic salt concentrations, recalcitrant compounds for SCWO process such as ammonia in a concentration range 3-8% in mass and suspensions of organic solids such as cellulose suspensions. Stable hydrothermal flames were observed, obtaining conversions over 99.99% for total organic carbon (TOC) and 99,90% for ammonia were reached which average effluent concentrations lower than 10 ppm TOC and 20 ppm total nitrogen (TN). Special care must be paid to in controlling reaction temperature and oxidant excess when working with nitrogen containing feeds, in order to avoid nitrate formation.