Supercritical Water Oxidation (SCWO) of Solid, Liquid and Gaseous Fuels for Energy Generation

Abstract

The SCWO (Supercritical Water Oxidation) process is well known for being able to destroy any kind of compound without producing prejudicial byproducts. This fact together with the high potential for energy production (because the high pressure high temperature effluent generated in the process) makes it a good candidate for generating energy from bio-fuels, especially those which valorization by conventional combustion can be problematic. In this work, different literature energetic studies of the SCWO process are analyzed. When comparing the heat produced by direct expansion of the effluent and by indirect heating steam generation it is observed that when direct expansion is used, the energetic efficiency is much higher than when the effluent is used to heat an auxiliary fluid of a Rankine or Brayton cycle. Nevertheless, the production of energy by direct expansion of the SCWO is not technically available in the short term. In any case, obtaining a high temperature effluent it is a key point for optimizing energy utilization. To do so, reactors in which the effluent is not diluted or reactor working at hydrothermal flame regime are desirable. Also the lay-out of the plant is important for energy utilization and factors as preheating scheme must be thoroughly studied. In addition to all of this, SCWO process has the additional advantage of the possibility of CO2 sequestration.