초록 ▼

Process and system are described for control of sulfur oxide in emissions to the atmosphere from regenerators of Fluid Catalytic Cracking Units (FCC) in a manner which improves the operation of the regenerator and/or the reactor. Spent FCC cracking catalyst containing sulfur-bearing inactivating car

Process and system are described for control of sulfur oxide in emissions to the atmosphere from regenerators of Fluid Catalytic Cracking Units (FCC) in a manner which improves the operation of the regenerator and/or the reactor. Spent FCC cracking catalyst containing sulfur-bearing inactivating carbonaceous deposit is partially oxidized, preferably in the presence of steam, thereby producing a mixture of CO and CO2 and releasing sulfur in the resulting reducing atmosphere as vaporous hydrogen sulfide before the catalyst is regenerated, whereby the amount of sulfur convertible to noxious SOx in the regenerator flue gas is reduced. By the disclosed process and system, the quantity of oxygen introduced is predetermined and controlled in response to hydrogen content of the coke on the partially oxidized catalyst or an SOx analyzer associated with the regenerator can be used as a control tool. Preferably, spent catalyst is partially oxidized in the presence of steam in a vessel separate from the regenerator and reactor, whereby the effluent can be utilized as a source of low BTU gas.

대표청구항 ▼

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 reac

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.