| abstract |
Oxides of nitrogen (NO x ) emissions from an FCC regenerator are reduced by forcing the regenerator to operate between full and partial CO burn mode. Operating with less than 1 mole % O2 and up to 1 or 2% CO in the flue gas creates conditions which oxidize nitrogen compounds in coke on spent catalyst to NOx, and simultaneously convert NOx in the regenerator to nitrogen. A downstream CO boiler can burn this low CO flue gas without producing large amounts of NOx. Most NOx emissions can be eliminated. An apparatus, with the regenerator air:coke ratio controlled by both CO and O2 analyzers monitoring regenerator flue gas, is also disclosed. |