Fluid catalytic cracking unit with low emissions

Abstract

An FCC unit enables the normal regenerator to be eliminated by carrying out catalyst regeneration in the reactor section of the unit using air, oxygen-enriched air or even relatively pure oxygen as the stripping medium in the stripping section of the reactor while maintaining overall reducing conditions so that sulfur and nitrogen are produced in the form of hydrogen sulfide, ammonia and other reduced species. The combustion gases from the stripper are sent from the reactor with the cracking vapors to the FCC main fractionator, wet gas compressor and gas plant to process the by-products of the coke combustion along with the FCC reactor effluent. The principle is applicable to grass-roots FCC units with its potential for elimination of a major unit component but it also has potential for application to existing units to reduce the load on the regenerator or eliminate the need for the existing regenerator so that an existing regenerator may be converted to a parallel or auxiliary reactor system.