The patented Zimmermann process involves flameless or wet combustion in aqueous solution or dispersions (Zimmermann 1954). Unlike other thermal processes, wet air oxidation does not require dewatering before combustion and creates no air pollution. In aqueous dispersion, a wide range of organic and hazardous industrial wastes can be oxidized to carbon dioxide and water by the addition of air or oxygen. Water, the bulk of the aqueous phase, catalyzes oxidation reactions so they proceed at relatively low temperatures (350-650°F). At the same time, water moderates the oxidation rates by evaporation.
Figure 11.14.8 shows a simplified flow scheme of a continuous air oxidation system. The waste liquor is mixed with air and is preheated by steam during process startup and by hot reactor effluent during operation to 300°-400°F. At this reactor inlet temperature oxidation starts, with the associated heat release further increasing the temperature as the liquid air mixture moves through the reactor. The higher the operating temperature, the greater the destruction of organic pollutants for the same residence time period. The operating temperature cannot
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