Experimental study of hydrothermal flames initiation using different static mixer configurations

The object of this work is to study by experiments the initiation of the SCWO reaction of concentrated IPA solutions, by mixing a water + IPA stream and an air stream in different static mixers at different operational conditions (temperature, fuel concentration, velocity). The start of the reaction was monitored experimentally measuring the temperature inside the mixer and by TOC determination in liquid samples. The experimental facility was modeled to assume plug flow and using different kinetic models in order to represent accurately the experimental data.It was found that at temperatures lower than 450–500 °C, depending on the mixer design, the reaction proceeded slowly, and when reaching higher temperatures the sharp increase indicated a much faster reaction mechanism. The description of the phenomenon is similar to the ignition of hydrothermal flames described in literature. In these cases TOC removals higher than 99% were reached in residence as low as 0.4 s. Ignition temperatures and minimum ignition injection temperatures were determined for the different mixers and experimental conditions.

Graphical abstractThe initiation of hydrotermal flames in tubular mixers was studied, obtaining extinction temperatures lower than 350 °C. Complete TOC removals were obtained in residence times shorter than 0.4 s.Figure optionsDownload full-size imageDownload as PowerPoint slide