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

Patent metadata

Field	Value
Publication number	US-2016115403-A1
Application number	US-201514887360-A
Country	US
Kind code	A1
Filing date	Oct 20, 2015
Priority date	Oct 22, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

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.

First claim

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.

2 . A hydrocracking process as recited in claim 1 , wherein said hydrocracking process is controlled so as to provide a weight ratio of said second portion of said heavy oil recycle stream to said first portion of said heavy oil recycle stream in the range upwardly to less than 0.5.

3 . A hydrocracking process as recited in claim 1 , wherein said at least two product streams further includes at least one light hydrocracker product and wherein said at least one light hydrocracked product is separated from said heavy oil recycle stream in a separation system, and a major portion of said heavy oil recycle stream is passed from said separation system to said hydrocracking reactor while a minor portion of said heavy oil recycle stream is passed from said separation system to said vacuum distillation unit.

4 . A hydrocracking process as recited in claim 2 , wherein said weight ratio of said second portion of the heavy oil recycle stream to said first portion of said heavy oil recycle stream is controlled so as to maintain said concentration of said polycyclic aromatic hydrocarbons to less than 1000 ppmw of said heavy oil recycle stream.

5 . A hydrocracking process as recited in claim 1 , wherein said least two product streams further includes at least one light hydrocracker product, wherein each of said at least one light hydrocracker product has an end point of less than 380° C. (716° F.).

6 . A hydrocracking process as recited in claim 3 , wherein the heavy oil recycle stream is the bottom stream from said separation system and comprises predominantly heavy hydrocarbons having a boiling point above 380° C. (716° F.).

7 . A hydrocracking process as recited in claim 5 , wherein said hydrocracking process provides for a conversion of said heavy feedstock of at least 50%, wherein said conversion is defined as the percentage of the hydrocarbons of said heavy feedstock boiling at or above 380° C. (716° F.) that is converted to hydrocarbons boiling below 380° C. (716° F.), based on the weight of said heavy feedstock.

8 . A hydrocracking process as recited in claim 4 , wherein said weight ratio of said second portion of the heavy oil recycle stream to said first portion of said heavy oil recycle stream is controlled so as to maintain said concentration of said polycyclic aromatic hydrocarbons to less than 500 ppmw of said heavy oil recycle stream.

9 . A hydrocracking process as recited in claim 8 wherein said hydrocracking process is controlled so as to provide a weight ratio of said second portion to said first portion is in the range of from 0.1 to 0.35.

10 . A hydrocracking process as recited in claim 9 , wherein said weight ratio of said second portion of the heavy oil recycle stream to said first portion of said heavy oil recycle stream is controlled so as to maintain said concentration of said polycyclic aromatic hydrocarbons to less than 250 ppmw of said heavy oil recycle stream.

11 . A hydrocracking process as recited in claim 7 , wherein said hydrocracking process provides for a conversion of said heavy feedstock of at least 75%.

Assignees

• Shell Oil Co

Inventors

• Macris Aristides

Classifications

• C10G67/049 Primary

  The hydrotreatment being a hydrocracking · CPC title

• C10G67/02 Primary

  plural serial stages only · CPC title

• C10G65/12

  including cracking steps and other hydrotreatment steps · CPC title

• C10G47/00

  Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions (C10G15/00 takes precedence; destructive hydrogenation of non-melting solid carbonaceous or similar materials C10G1/06) · CPC title

• C10G67/04 Primary

  including solvent extraction as the refining step in the absence of hydrogen · CPC title