Hydrocracking of heavy hydrocarbon oils with conversion facilitated by recycle of both heavy gas oil and pitch

• US 6,004,453 A
• Filed: 03/06/1998
• Issued: 12/21/1999
• Est. Priority Date: 12/21/1995
• Status: Expired due to Term

• Current Assignee: Her Majesty The Queen In Right Of Canada As Represented By The Minister Or Natural Resources
• Original Assignee: Petro-Canada (Suncor Energy Incorporated)
• Inventors: Roy, Michel, Pruden, Barry B., Benham, N. Kelly
• Primary Examiner(s): MYERS, HELANE ELEANORA
• Application Number:
  US09/035,915
• Time in Patent Office: 655 Days
• Field of Search: 208/112, 208/107, 208/48 R, 208/48 AA, 208/108, 208/100
• US Class Current: 208/108
• CPC Class Codes: C10G 47/22 Non-catalytic cracking in the presence of hydrogen
• CPC Class Codes: C10G 47/26 suspended in the oil, e.g. slurries

Abstract

A process for hydrocracking a heavy hydrocarbon oil feedstock, a substantial portion of which boils above 524° C. is described which includes the steps of: (a) passing a slurry feed of a mixture of heavy hydrocarbon oil feedstock and from about 0.01-4.0% by weight (based on fresh feedstock) of coke-inhibiting additive particles upwardly through a confined vertical hydrocracking zone, the hydrocracking zone being maintained at a temperature between about 350° and 600° C. a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrocracking zone capacity, (b) removing from the top of the hydrocracking zone a mixed effluent containing a gaseous phase comprising hydrogen and vaporous hydrocarbons and a liquid phase comprising heavy hydrocarbons, (c) passing the mixed effluent into a hot separator vessel, (d) withdrawing from the top of the separator a gaseous stream comprising hydrogen and vaporous hydrocarbons, (e) withdrawing from the bottom of the separator a liquid stream comprising heavy hydrocarbons and particles of the coke-inhibiting additive, and (f) fractionating the separated liquid stream to obtain a heavy hydrocarbon stream which boils above 450° C. said heavy hydrocarbon stream containing said additive particles, and a light oil product. According to the novel feature, at least part of the fractionated heavy hydrocarbon stream boiling above 450° C. is recycled to form part of the heavy hydrocarbon oil feedstock at a lower polarity aromatic oil is added to the heavy hydrocarbon oil feedstock such that a high ratio of lower polarity aromatics to asphaltenes is maintained during hydroprocessing. This provides excellent yields without coke formation.

Claims

1. A process for hydrocracking a heavy hydrocarbon oil feedstock, a substantial portion of which boils above 524°

C. which comprises;

(a) preparing a slurry feed of a mixture of heavy hydrocarbon oil feedstock and from about 0.01-4.0% by weight (based on fresh feedstock) of coke-inhibiting additive particles selected from the group consisting of coal, non-coal, fly ash, pyrite and iron compounds which are not active hydrogenation catalysts, passing said slurry feed upwardly through a confined vertical hydrocracking zone in the presence of hydrogen and in the absence of an active hydrogenation catalyst, said hydrocracking zone being maintained at a temperature above about 450°

C., a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrocracking zone capacity,

(b) removing from the top of said hydrocracking zone a mixed effluent containing a gaseous phase comprising hydrogen and vaporous hydrocarbons and a liquid phase comprising heavy hydrocarbons,

(c) passing said mixed effluent into a hot separator vessel,

(d) withdrawing from the top of the separator a gaseous stream comprising hydrogen and vaporous hydrocarbons,

(e) withdrawing from the bottom of the separator a liquid stream comprising liquid hydrocarbons and particles of the coke-inhibiting additive,

(f) fractionating the separated liquid stream to obtain a pitch bottom stream which boils above 495°

C., said pitch stream containing said additive particles, and an aromatic heavy gas oil fraction boiling in the range of 360 to 524°

C.,

(g) recycling at least part of said pitch stream containing additive particles to form about 5 to 15% by weight of the feedstock to the hydrocracking zone, and

(h) recycling at least part of said aromatic heavy gas oil fraction to form about 15 to 50% by weight of the feedstock to the hydrocracking zone.

2. Process according to claim 1 wherein the hydrocracking zone is maintained at a temperature above about 470°

C.

3. Process according to claim 2 wherein the aromatic heavy gas oil has a boiling point above about 400°

C.

4. Process according to claim 1 wherein the heavy hydrocarbon oil feedstock is a visbroken vacuum residue.

5. Process according to claim 1 wherein the heavy hydrocarbon oil feedstock is an asphaltene rich product from a deasphalting process.

6. Process according to claim 1 wherein the heavy hydrocarbon oil feedstock is processed prior to hydrocracking to remove high boiling paraffinic material.

7. Process according to claim 1 wherein part of the fractionated heavy hydrocarbon stream boiling above 450°

C. comprises a pitch product of the process and this pitch is fed to a thermal cracking process.

8. Process according to claim 1 wherein the aromatic heavy gas oil contains about 100 to 110% of the feed nitrogen concentration.

9. Process according to claim 1 wherein the coke-inhibiting additive particles have sizes of less than about 45 μ

m.