Supercritical hydrothermal combustion of nitrogen-containing compounds in a tubular reactor

Abstract

Supercritical hydrothermal combustion is a promising approach for disposal of nitrogen-containing pollutants. The hydrothermal combustion characteristics of two typical nitrogen-containing compounds, ammonia and quinoline, were systematically explored in a continuous supercritical water tubular reactor. The ignition and combustion of two auxiliary fuels of methanol and ethanol were compared first. The combustion reaction for ammonia and quinoline with the presence of methanol was investigated, respectively. The result indicated that ethanol could ignite more easily than methanol, while the combustion rate of methanol was faster than that of ethanol. Ammonia/methanol was capable of ignition in supercritical water, depending on the initial fuel concentration, preheating temperature, and ammonia ratio. And ammonia could promote the overall combustion process at fuel COD concentration of 73.0 g/L, preheating temperature of 420 ℃ and ammonia ratio of 0.05–0.19. Moreover, this experiment also verified that 2.74 wt% quinoline could undergo ignition in dynamic flow of the supercritical water reactor, and the oxidation reaction mechanism of quinoline was further analyzed.