Main column separation of FCC product effluent

Claim 1

In a fluid catalytic cracking process, wherein a hydrocarbonaceous charge stock is converted into lower-boiling hydrocarbons in contact with finely-divided catalyst particles, the method of separating catalyst-containing, catalytically-cracked product effluent which comprises the steps of: a. introducing said product effluent into a first fractionation column through a first locus in the bottom portion thereof; b. withdrawing a light naphtha fraction from a second locus in the upper portion of said column, condensing and separating said light naphtha fraction to provide (i) a first vaporous phase and, (ii) a liquid phase; c. recycling a first portion of said liquid phase, as a reflux stream, to said first column through a third locus below said second locus, and introducing a second portion into a second fractionation column; d. separating said second portion to provide (i) a second vaporous phase and, (ii) a light naphtha product stream; e. withdrawing a heavy naphtha fraction from said first column, through a fourth locus below said third locus, and introducing at least a portion thereof into a third fractionation column; f. separating the portion of said heavy naphtha fraction to provide (i) a heavy naphtha bottoms product stream substantially free from light naphtha and, (ii) a light naphtha containing overhead stream; g. introducing at least a portion of said overhead stream into said first column through a fifth locus intermediate said third and fourth loci; and, h. withdrawing a catalyst-containing slurry oil fraction from said first column through a sixth locus below said first locus.