Supercritical water gasification of waste residues

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] A batch reactor was built in the University of Missouri Carbon Recycling Center to explore the thermo-chemical conversion of motor oil as a model compound, in supercritical water. Used motor oil was identified as a main waste compound leading to increased land fill concerns and supercritical water gasification is introduced as a method of decomposing such waste residues with high efficiencies. This study focused on supercritical water gasification of motor oil using a batch reactor operated between 750°C - 800°C. The specific goals were to determine the gasification efficiencies, to compare the effect of emulsification of motor oil on the efficiencies, and to model the gasification reaction. The gas product was analyzed by gas chromatography and a 22 full factorial was performed to identify the effects of the process variables on each component of the gaseous product. The three process variables explored in this investigation are emulsification of motor oil with water, residence time and, inlet MO concentration. Finally, the Arrhenius equation was used to model the reaction. The model parameters estimated were the pre-exponential factor (2·104 (g/ml)0.15/s), activation energy (94 kJ/mol) and the reaction order (0.85).