Method for reducing catalyst particle emissions in fluidized catalytic cracking processing

摘要

An improvement in a process for catalytic cracking of hydrocarbon feedstocks which comprises reducing the emisssion of catalyst particles through a regenerator effluent gas by passing a catalyst-laden stream from a main column into a slurry settling zone where there is recovered a decanted oil from an upper portion of said zone and an oil (slurry and oil) of catalyst from a bottom portion of said slurry settler. The improvement comprises recycling at least a portion of the decanted oil from said zone to a lower portion of the zone so as to regulate the upward velocity of the oil in said zone to selectively reject through the decanted oil stream small catalyst particles (less than about 20 microns diameter), which if not rejected through the decanted oil stream, would be recycled back to a fluidized catalytic cracking reaction zone in the slurry oil stream and ultimately released to the atmosphere by the effluent gases from the regeneration zone.