| 摘要 |
A process for treating an exhaust stream which includes high levels of noxious compounds containing chemically bound nitrogen, to produce an effluent stream that is extremely low in oxides of nitrogen and environmentally safe for discharge into the atmosphere. A source of oxygen and fuel is added to the exhaust stream to create a fuel-rich mixture, the quantity of fuel being sufficient to react with the available oxygen. The fuel-enriched stream is provided to a thermal reactor and reacted to provide a heated oxygen-depleted stream which includes quantities of by-product NOx, which stream is then cooled to 800 DEG to 1000 DEG F. Conversion oxygen is added to the cooled stream which is then passed over a first catalyst bed under overall reducing conditions, the quantity of conversion oxygen added being in stoichiometric excess of the amount of NOx in the stream, but less than the amount of combustibles, whereby the NOx is first oxidized to NO2, and then the NO2 is reduced by the excess combustibles. The stream is cooled to a temperature of about 450 DEG to 550 DEG F., and air is added to produce a further cooled stream at a temperature of about 400 DEG to 500 DEG F., and having a stoichiometric excess of oxygen. This is passed over an oxidizing catalyst bed to oxidize remaining excess combustibles, and provide an effluent stream having environmentally safe characteristics. |
