Modeling of supercritical oxidation of aqueous wastes in a deep‐well reactor

Abstract

AbstractA mathematical model is developed for deep‐well oxidation of wastes in supercritical water. The model accounts for the variation of thermodynamic and transport properties with temperature and pressure. It is used to examine the steady‐state behavior of the supercritical‐water deep‐well oxidation reactors. The effects of inlet flow rate, heat losses from the reactor, inlet concentration of organics, oxygen injection depth, reactor length, inlet pressure, and inlet temperature on the exit conversion and the bottom temperature are examined. The simulations show that under practical conditions the capacity of the reactor is dictated by hydrodynamic considerations rather than the oxidation kinetics, and that obtaining temperatures of 10 to 50 K above critical temperature at the bottom of the reactor requires longer tubes and/or high inlet pressures. Heat losses to the earth can be modeled accurately by treating the earth as an infinite reservoir by properly choosing the effective heat‐transfer coefficient.