Reacting flow simulations of supercritical water oxidation of PCB-contaminated transformer oil in a pilot plant reactor

Abstract

-The scale-up of a supercritical water oxidation process, based on recent advancements in kinetic aspects, reactor configuration and optimal operational conditions, depends on the research and development of simulation tools, which allow the designer not only to understand the complex multiphysics phenomena that describe the system, but also to optimize the operational parameters to attain the best profit for the process and guarantee its safe operation. Accordingly, this paper reports a multiphysics simulation with the CFD software Comsol Multiphysics 3.3 of a pilot plant reactor for the supercritical water oxidation of a heavily PCBcontaminated mineral transformer oil. The proposed model was based on available information for the kinetic aspects of the complex mixture and the optimal operational conditions obtained in a lab-scale continuous supercritical water oxidation unit. The pilot plant simulation results indicate that it is not feasible to scale-up directly the optimal operational conditions obtained in the isothermal lab-scale experiments, due to the excess heat released by the exothermic oxidation reactions that result in outlet temperatures higher than 600°C, even at reactor inlet temperatures as low as 400°C. Consequently, different alternatives such as decreasing organic flowrates or a new reactor set-up with multiple oxidant injections should be considered to guarantee a safe operation.

Applications of Supercritical Fluids in Latin America: Past, Present and Future Trends

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Mn–Ce–Co complex oxide nanoparticles: Hydrothermal synthesis and their catalytic subcritical oxidation of 4,4′-Dibromobiphenyl

“…Supercritical water oxidation (SCWO) is a very effective way to degrade organic pollutants because most organic pollutants and oxidants can dissolve in supercritical water to form a homogeneous phase [8][9][10][11][12][13][14][15]. Although SCWO shows great potential in degradation of organic pollutants, many problems such as deposition of salts, corrosion, and the high temperature and pressure of the critical point of 647 K and 22.1 MPa cause it very difficult to be applied to industrial utilization.…”