Hydrocracking process integrated with vacuum distillation and solvent dewaxing to reduce heavy polycyclic aromatic buildup

摘要

An integrated hydrocracking, vacuum distillation and solvent deasphalting process that provides for controlling the amount of polycyclic aromatic hydrocarbons in a heavy oil recycle stream by separating a portion of the heavy oil recycle stream into various fractions in a vacuum distillation unit, and processing the various fractions in a manner, including solvent deasphalting, that allows for the control of the polycyclic aromatic hydrocarbons in the heavy oil recycle stream.

主权项

1. A hydrocracking process providing for a reduction of the buildup of polycyclic aromatic hydrocarbons in a heavy oil recycle stream of said hydrocracking process, wherein the process comprises:
(a) hydrocracking in a hydrocracker reactor a heavy feedstock to yield a hydrocracked product that is separated into at least two product streams including said heavy oil recycle stream, comprising a concentration of said polycyclic aromatic hydrocarbons; (b) passing a first portion of said heavy oil recycle stream as a recycle feed to said hydrocracker reactor; (c) passing a second portion of said heavy oil recycle stream to a vacuum distillation unit wherein said second portion is separated into at least a light vacuum gas oil stream, a heavier vacuum gas oil stream, a slop oil/wax stream and a vacuum resid stream, and wherein said light vacuum gas oil stream contains a concentration of polycyclic aromatic hydrocarbons greater than the concentration of polycyclic aromatic hydrocarbons in said heavier vacuum gas oil stream; (d) passing said heavier vacuum gas oil stream as a feed to said hydrocracker reactor; (e) using said light gas oil stream containing said higher concentration of polycyclic aromatic compounds as a bleed stream or a product stream that is not returned to said hydrocracking process; (f) passing the slop oil/wax stream and the vacuum resid stream to a solvent deasphalting unit wherein asphaltenes and heavy polycyclic aromatic hydrocarbons are separated from said streams to yield a deasphalted paraffinic oil depleted in polycyclic aromatic hydrocarbons; and (g) passing said deasphalted paraffinic oil depleted in polycyclic aromatic hydrocarbons as a feed to said hydrocracker reactor.