US-12624301-B2 - Processes for upgrading hydrocarbon feedstock

Abstract

A process for upgrading a hydrocarbon feedstock may include introducing a hydrocarbon feedstock into a hydrocracking unit to obtain a hydrocracked product, introducing the hydrocracked product to a fractionation unit to obtain distillates and unconverted oil, the unconverted oil having a boiling point greater than 375° C., introducing the unconverted oil and supercritical water to a supercritical water unit to obtain a treated product, wherein the supercritical water has a pressure greater than 21 MPa and a temperature above 374° C., and separating the treated product to obtain a purified product and a concentrated product, wherein the concentrated product includes heavy polynuclear aromatics (HPNA).

Inventors

• Ki-Hyouk Choi
• Young-Kyoung Ahn
• Mamdouh Abdoun Al-Harbi

Assignees

• SAUDI ARABIAN OIL COMPANY

Dates

Publication Date

20260512

Application Date

20240212

Claims (18)

1. 1 . A process for upgrading a hydrocarbon feedstock, the process comprising: introducing a hydrocarbon feedstock into a hydrocracking unit to obtain a hydrocracked product; introducing the hydrocracked product to a fractionation unit to obtain distillates and unconverted oil, the unconverted oil having a boiling point greater than 375° C.; introducing the unconverted oil and supercritical water to a supercritical water unit to obtain a treated product, wherein the supercritical water has a pressure greater than 21 MPa and a temperature above 374° C. and a ratio of a flow rate of the supercritical water to a flow rate of the unconverted oil is from 20:1 to greater than 10:1 when the unconverted oil and the supercritical water are introduced to the supercritical water unit; and separating the treated product to obtain purified product and a concentrated product, wherein the concentrated product comprises heavy polynuclear aromatics (HPNA).
2. 2 . The process of claim 1 , wherein the unconverted oil has a residence time within the supercritical water unit of from 10 seconds to 60 minutes within the supercritical reactor.
3. 3 . The process of claim 1 , further comprising recycling at least a portion of the purified product to the hydrocracking unit.
4. 4 . The process of claim 1 , further comprising mixing the unconverted oil and the supercritical water before introducing the unconverted oil and the supercritical water to the supercritical water unit.
5. 5 . The process of claim 1 , wherein the feedstock comprises less than or equal to 800 ppmw heavy polynuclear aromatics.
6. 6 . The process of claim 1 , wherein the supercritical water is demineralized water comprising: a conductivity of less than 1 μS/cm; a sodium content of less than 5 μg/L; a chloride content of less than 5 μg/L; and a silica content of less than 3 μg/L.
7. 7 . The process of claim 1 , wherein the supercritical water unit operates at a pressure greater than 21 MPa and a temperature of from 374° C. to 600° C.
8. 8 . The process of claim 1 , wherein the supercritical water has a pressure greater than 21 MPa and a temperature of from 400° C. to 700° C. before the supercritical water is introduced into the supercritical water unit.
9. 9 . The process of claim 1 , wherein the unconverted oil has a pressure greater than 21 MPa and a temperature of from 50° C. to 350° C. before the supercritical water is introduced into the supercritical water unit.
10. 10 . The process of claim 1 , wherein fluid in the supercritical water unit is in a turbulent flow regime with a Reynolds number greater than 3,000.
11. 11 . The process of claim 1 , wherein the hydrocracking unit operates at a pressure of from 5 to 25 MPa, a temperature of from 300° C. to 600° C., and the feedstock has a liquid hourly space velocity of from 0.05 to 3 hr −1 .
12. 12 . The process of claim 1 , wherein the hydrocarbon feedstock is vacuum gas oil (VGO).
13. 13 . The process of claim 1 , wherein the hydrocracked product comprises from 0 to 50 wt. % unconverted oil.
14. 14 . The process of claim 1 , wherein separating the treated product to obtain the purified product and the concentrated product comprises passing the treated product to an extraction device, a fractionation device, or a filtration device to obtain the purified product and the concentrated product.
15. 15 . The process of claim 1 , wherein separating the treated product to obtain the purified product and the concentrated product comprises: separating the treated product in a gas-liquid separator to obtain a gas product and a liquid product; separating the liquid product in an oil-water separator to obtain a water product and an oil product; and passing the oil product to an extraction device, a fractionation device, or a filtration device to separate the oil product to obtain the purified product and the concentrated product.
16. 16 . The process of claim 1 , wherein the purified product comprises from 0 to 35 ppmw heavy polynuclear aromatics.
17. 17 . The process of claim 1 , further comprising using the heavy polynuclear aromatics to form pitch.
18. 18 . The process of claim 17 , wherein the pitch is mesophase pitch.

Description

TECHNICAL FIELD Embodiments described herein generally relate processes for upgrading hydrocarbon feedstock. BACKGROUND Hydrocracking processes crack large hydrocarbon compounds into smaller hydrocarbon compounds with aid of a catalyst and hydrogen to produce products that can be used in fuels and chemical feedstocks. Hydrocracking catalysts typically suffer from coking, which shortens the catalyst life. Coke precursors, present in feed materials or formed in the reactor, undergoes coupling, condensation, cyclization, aromatization, and dehydrogenation to form coke materials on catalyst. Coke is formed from strongly adsorbed aromatic compounds on the catalyst surface and subsequent condensation reactions. Severity of the process conditions may be increased to compensate for the reduced catalyst activity caused by coking. However, greater severity of the process accelerates coke formation and eventually catalyst deactivation. In general, typical hydrocarbon feedstocks used for hydrocracking, such as vacuum gas oil (VGO), contain 2-6 ring polynuclear aromatics. Through coupling or condensation reactions that occur at the high temperatures typically used for hydrocracking, the ring size may increase to form heavy polynuclear aromatics. Heavy polynuclear aromatics contain 7+ aromatic rings, are uncharged, non-polar, and planar in structure, and are highly effective coke precursors. Heavy polynuclear aromatics are produced by coupling or condensation of smaller polynuclear aromatics and single ring aromatics during the hydrocracking reaction. Heavy polynuclear aromatics are inert under conventional hydrocracking conditions, so the heavy polynuclear aromatics are not typically decomposed or hydrogenated. Therefore, improved methods of upgrading hydrocarbon feedstocks that address catalyst deactivation caused by heavy polynuclear aromatics are needed. SUMMARY Embodiments of the present disclosure meet this and other needs by utilizing supercritical water processing to reduce heavy polynuclear aromatics in upgraded hydrocarbons. The process may include introducing a hydrocarbon feedstock into a hydrocracking unit to obtain a hydrocracked product, introducing the hydrocracked product to a fractionation unit to obtain distillates and unconverted oil, the unconverted oil having a boiling point greater than 375° C., introducing the unconverted oil and supercritical water to a supercritical water unit (SCW) to obtain a treated product, wherein the supercritical water has a pressure greater than 21 MPa and a temperature above 374° C., and separating the treated product to obtain a purified product and a concentrated product, wherein the concentrated product includes heavy polynuclear aromatics (HPNA). It is to be understood that both the preceding general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. Additional features and advantages of the embodiments will be set forth in the detailed description and, in part, will be readily apparent to persons of ordinary skill in the art from that description, which includes the accompanying drawings and claims, or recognized by practicing the described embodiments. The drawings are included to provide a further understanding of the embodiments and, together with the detailed description, serve to explain the principles and operations of the claimed subject matter. However, the embodiments depicted in the drawings are illustrative and exemplary in nature, and not intended to limit the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS The following detailed description may be better understood when read in conjunction with the following drawings, in which: FIG. 1 illustrates a schematic view of an example system for upgrading a hydrocarbon feedstock that may be suitable for use with the processes for upgrading hydrocarbon feedstock. FIG. 2 illustrates a schematic view of an example setup of the SCW unit. FIG. 3 illustrates a schematic view of a comparative process for upgrading a hydrocarbon feedstock. DETAILED DESCRIPTION The present disclosure is generally directed to a process for upgrading hydrocarbon feedstock. The process may generally include introducing a hydrocarbon feedstock into a hydrocracking unit to obtain a hydrocracked product, introducing the hydrocracked product to a fractionation unit to obtain distillates and unconverted oil, the unconverted oil having a boiling point greater than 375° C., introducing the unconverted oil and supercritical water to a supercritical water unit to obtain a treated product, wherein the supercritical water has a pressure greater than 21 MPa and a temperature above 374° C., and separating the treated product to obtain a purified product and heavy polynuclear aromatics. As used in this disclosure, a “catalyst” refers to any inorganic substances other than water that increases