Deep well oxidation is a novel process that has been developed recently for oxidizing suspended and dissolved organics from dilute aqueous waste streams. The process employs wet oxidation methods and is carried out in a deep well reactor buried in the ground. The reactor consists of concentric tubes of length 1.500 -3.000 meters suspended within a conventionally drilled and cased well. In the oxidation process, the waste stream and oxygen are brought together in a mixture at high pressure and elevated temperature. Organic oxidation is initiated spontaneously at these conditions. The heat of combustion is used to heat up the incoming feed to the required temperature and the hydrostatic head provides the required Pressure. Thii work presents a simplified mathematical model of the deep well reactor that describes the behavior when it is operated in the subcritical region. The model accounts for the lumped kinetics of oxidation, fluid flow, heat transfer between the tubes and heat losses to the surrounding earth. It ia used to investigate the influence of various design and operating parameters on the steady-state behavior of the reactor. KEYWORDS Deep well reactor, aqueous waste. wet oxidation, ignition, extinction. B'JTRODUCTION The deep well oxidation process has been developed recently for oxidizing suspended and dissolved organics from aqueous waste sue-.
This process is expected to be very effective at treating aqueous waste streams that are too dilute to incinerate economically, yet too toxic to treat biologically or by other means. Some waste streams can be treated effectively under subcritical conditiona at temperatures of 3OO-35O'C and pressures of 14-18 MPa while others can only be treated at supercritical conditions above the critical point of water (374OC and 22.1 MPa). The subcritical process is ideal for treating wastes such as municipal sewage or hazardous aqueous streams containing low percentages of hydrocarbons while the supercritical process is expected to be applicable to a broader range of more toxic aqueous wastes.