Patent FR-2814967-A1 (FR)
Title: Hydrothermal oxidation, for decontamination of materials, uses heated supercritical liquid with oxidant under pressure within inner tube of reactor, with agitation, followed by cooling for extraction
Inventor: JOUSSOT DUBIEN CHRISTOPHE
IPC: B01J19/18
Filed: 2000-10-10
Abstract: To apply a hydrothermal oxidizing process to materials, a liquid of water and an oxidant is fed into a ring zone at a pressure of \-22.1 MPa, defined by one end of a twin-wall tubular reactor. It is heated at the ring zone to \-374 deg C to be fed into the reactor inner tube with a simultaneous feed of the materials from the other end. The liquid and the materials mix together at one section of the inner tube, and are cooled in a second section of the tube. The chilled and oxidized mixture is extracted by an isobaric evacuation from the inner tube at the first end of the reactor. The fluids and materials have a continuous or quasi continuous flow.  The hydrothermal oxidizing process, to treat materials, evacuates them by a counter flow of the heating for the liquid/oxidant. The liquid/oxidant and the materials to be treated, under heat and pressure, are mixed by agitation within the inner tube, to a condition which is present in the reactor to give batches to be passed into the reactor. The mixture is chilled by a strong agitation. The material to be treated is a waste product. The oxidant is a gas of ozone and a mixture of ozone and nitrogen, or a liquid of hydrogen peroxide and liquid oxygen. The oxidant is fed into the reactor with water at a rate of 1-5 times the necessary stoichiometric amount to oxidize the material.  An Independent claim is included for an apparatus (1) to oxidize materials, in a supercritical environment, with a tubular body (3) with a flange (5) and seal (7) at one end. It has an entry (9) for the constituents of the supercritical environment, and an outlet (11) for the treated materials. The flange has a sealed passage (13) for a rotating shaft (15). The other end has a feed opening (17) for the materials to be treated. The apparatus is constructed of materials which are resistant to the pressure and temperature of the supercritical environment. Preferred Features: An inner tube (19) is within the body, to form a ring zone (21) along the body. The inner tube has a passage (23) through it, with two ends (25,27) to give a sealed entry at the flange leading to the outlet for the treated material. The other end gives a link into the passage for the second feed opening directly into the tube passage without reflux towards the ring zone. The agitation system (29) is within the tube passage, operated by the rotating shaft. The cooling system (31) is around the body, at a section to act on the treated material within the inner tube, before it is extracted through the outlet, as a twin-jacket refrigeration unit.. The heating system (33) is around the body at a section to act on the supercritical environment, and heat its constituents before they enter the inner tube at the second end, as a heating sleeve. A metal cladding is wholly or partially around the ring zone. The material to be treated is injected directly into the inner tube at the second end, using an injection tube (35) with a smaller diameter than the inner tube. The inner tube has a thickness of 1 mm. The rotating shaft is powered by a drive motor, coupled to a frequency control to give a rotary speed of 0-1500 rpm. The agitation system has rotary paddles (37) forming a spiral, a turbine, a flat paddle and an anchor. The inner tube and the agitation mechanism are of identical materials of stainless steel, a nickel alloy resistant to heat and oxidizing, an alloy of Ni58 or Fe20 or Mo201, titanium and ceramics.