Inverted fractionation apparatus and use in a heavy oil catalytic cracking process

摘要

A process and apparatus for fractionation of a superheated vapor in a fractionation column is disclosed. A conventional fractionator, having an inlet for hot vapors at the base, and a plurality of products withdrawn via side draws is modified by physically inverting some parts of the column. The superheated vapors are charged to an upper portion of the column, to contact and vaporize a liquid fraction pumped up from a lower portion of the column. The vaporized liquid is discharged as a vapor fraction to the base of the column from which the liquid fraction was obtained. Superheated vapor fed to the column is fractionated, but in a fractionator in which the hottest part of the column is not in the base of the column. The inverted fractionator, when used in conjunction with a riser cracking FCC reactor, greatly reduces thermal cracking in a transfer line moving superheated, cracked vapor from the reactor to the fractionator. The inverted fractionator improves yields, and permits higher cracking reactor temperatures to be used.