Control of emissions in FCC regenerator flue gas

  • US 4,274,942 A
  • Filed: 04/04/1979
  • Issued: 06/23/1981
  • Est. Priority Date: 04/04/1979
  • Status: Expired due to Term
First Claim
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1. In a process for catalytic cracking of a sulfur containing hydrocarbon charge by contacting said charge at cracking temperature with a circulating inventory of cracking catalyst whereby the catalyst acquires an inactivating carbonaceous deposit containing sulfur, separating vaporous products of reaction from circulating catalyst inventory containing said carbonaceous deposit, regenerating said inventory with air at a temperature to burn said carbonaceous deposit thus generating oxides of carbon and sulfur and regenerating the catalyst, separating products of combustion from regenerated catalyst, and returning regenerated catalyst to renewed contact with hydrocarbon charge, the improvement which comprises:

  • regenerating said separated inventory by first contacting it with a source of O2 in the presence of steam using a predetermined quantity of O2 so limited as to partially oxidize carbon in said carbonaceous deposit while eliminating substantially all hydrogen therein, said contacting being further characterized by the use of steam in amount such that a reducing atmosphere is created by steam and by carbon monoxide resulting from partial oxidation of said carbon and being carried out under conditions to substantially reduce the content of sulfur in said carbonaceous deposit and produce vaporous products of partial oxidation essentially free from oxides of sulfur and including hydrogen sulfide, carbon monoxide, as aforesaid, carbon dioxide and water vapor, separating said vaporous products of partial oxidation from the resulting partially regenerated inventory containing residual carbon now having a substantially reduced sulfur content, thereafter contacting said partially regenerated inventory with air to burn residual carbonaceous deposit and separating products of combustion from regenerated catalyst, whereby there are reduced amounts of oxides of sulfur and carbon in said products of combustion separated from regenerated catalyst as a result of prior reduction in the amount of sulfur and carbon in said carbonaceous deposit by partial oxidation as aforementioned.

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