Hydrocracking process

Patent metadata

Field	Value
Publication number	US-11898108-B2
Application number	US-202217841829-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Jun 17, 2021
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A process for hydrocracking a petroleum feedstock involves:(a) hydrocracking the feedstock to obtain a hydrocracked effluent;(b) liquid/gas separation of the effluent to obtain a gaseous effluent and a liquid effluent;(c) fractionating the liquid effluent at a pressure P1, producing a first distillate and a first residue,(d) recycling a first portion of the first residue to hydrocracking,(e) rectifying a second portion of the first residue at a pressure P2 lower than or equal to the pressure P1, to obtain a secondary distillate, a secondary residue and a vapor stream,(f) purging a portion of the secondary residue, and(g) recycling all or part of the secondary distillate to hydrocracking.

First claim

The invention claimed is:

1. A process for hydrocracking a petroleum feedstock ( 1 ) comprising at least 10% by volume of compounds that boil above 340° C., said process comprising:
(a) at least one step of hydrocracking the feedstock in order to obtain a hydrocracked effluent;
(b) a step of liquid/gas separation of the hydrocracked effluent in order to obtain a gaseous effluent ( 5 ) and a liquid effluent ( 9 );
(c) a step of fractionating said liquid effluent ( 9 ), in at least one fractionating column ( 12 ), at a pressure P1 at the bottom of the column, to produce at least a first distillate ( 13 , 14 ) and a first residue ( 15 ),
(d) a step of recycling a first portion ( 18 ) of said first residue ( 15 ) to the hydrocracking step and/or at least one of the hydrocracking steps,
(e) a step of rectifying a second portion ( 20 ) of the first residue ( 15 ) obtained in the fractionating step, carried out in at least one column ( 21 ), at a pressure P2 at the top thereof which is at least 0.05 MPa lower than pressure P1, to obtain at least a secondary distillate ( 23 ), a secondary residue ( 16 ) and a vapor stream ( 22 ),
(f) a step of purging at least one portion or all of the secondary residue ( 16 ),
(g) a step of recycling all or part of said secondary distillate ( 23 ) to the hydrocracking step or to at least one of the hydrocracking steps, after an optional gas separation step.

2. The process according to claim 1 , wherein said process is free of a step of recycling, to the fractionating step (c), all or part of the secondary distillate ( 23 ) and/or all or part of the secondary residue ( 16 ) and/or all or part of the overhead vapor stream ( 22 ) which result from the rectifying step (e).

3. The process according to claim 1 , wherein the pressure P2 at the top of the column ( 21 ) of the rectifying step is lower than the pressure P1 in the bottom of the column of the fractionating step (c) by at least 0.06 MPa.

4. The process according to claim 1 , wherein the pressure P2 at the top of the column ( 21 ) of the rectifying step (e) is lower than atmospheric pressure.

5. The process according to claim 1 , wherein the rectifying step (e) uses a distillation column ( 21 ) equipped with feed tray(s), optionally with packing and with draw-off tray(s), and in that:
the first residue ( 15 ) from the fractionating step (c), optionally at least partially vaporized, feeds said distillation column ( 21 ) at at least one feed tray,
the secondary distillate ( 23 ) is drawn off from said distillation column ( 21 ) at a draw-off tray,
the secondary residue ( 16 ) is drawn off at the bottom of said distillation column ( 21 ), and
the overhead vapor stream ( 22 ) is cooled.

6. The process according to claim 1 , wherein the rectifying step (e) uses a distillation column ( 21 ) equipped with feed tray(s), optionally with packing and with draw-off tray(s), and step (e) is carried out with a stripping gas.

7. The process according to claim 1 , wherein, in the rectifying step (e), the first residue ( 15 ) is fed at a temperature of between 250° C. and 400° C.

8. The process according to claim 1 , wherein the second portion ( 20 ) of the first residue ( 15 ) which is treated in the rectifying step (e) corresponds to at most 50% by weight of the first residue obtained in the fractionating step (c).

9. The process according to claim 1 , wherein, in the purging step (f), at least 20% by weight of the secondary residue ( 16 ) is purged.

10. The process according to claim 1 , wherein the fractionating step and/or the rectifying step are carried out with a stripping gas.

11. The process according to claim 10 , wherein the stripping gas of the fractionating step is injected at a pressure of between 0.2 and 0.4 MPa, and/or the stripping gas of the rectifying step is injected at a pressure of between 0.001 and 0.35 MPa.

12. The process according to claim 1 , wherein said process has one or two hydrocracking steps (a), and at least one of said one or two hydrocracking steps is preceded by a hydrotreating step (h).

13. The process according to claim 1 , wherein the pressure P2 at the top of the column ( 21 ) of the rectifying step is lower than the pressure P1 in the bottom of the column of the fractionating step (c) by at least 0.08 MPa.

14. The process according claim 1 , wherein the pressure P2 at the top of the column ( 21 ) of the rectifying step (e) is between 1333 Pa and 0.08 MPa.

15. The process according to claim 1 , wherein the second portion ( 20 ) of the first residue ( 15 ) which is treated in the rectifying step (e) corresponds to at most 20% by weight of the first residue obtained in the fractionating step (c).

16. The process according claim 1 , wherein, in the purging step (f), at least 40% by weight of the secondary residue ( 16 ) is purged.

17. The process according to claim 1 , wherein said process is free of a step of recycling, to the fractionating step (c), all or part of the overhead vapor stream ( 22 ) resulting from the rectifying step (e).

18. The process according to claim 1 , wherein pressure P1 is between 0.2 and 0.4 MPa.

19. A plant for hydrocracking a petroleum feedstock comprising at least 10% by volume of compounds that boil above 340° C., said plant successively comprising:
(a) at least one section ( 2 ) for hydrocracking the feedstock ( 1 ) in order to obtain a hydrocracked effluent,
(b) at least one section ( 4 ) for liquid/gas separation of the hydrocracked effluent in order to obtain a gaseous effluent ( 5 ) and a liquid effluent ( 9 ),
(c) a section for fractionating said liquid effluent, comprising at least one column ( 12 ), at a pressure P1 at the bottom of the column, to produce at least a first distillate ( 13 , 14 ) and a first residue ( 15 ),
(d) a line for recycling a first portion ( 18 ) of said first residue ( 15 ) to one of the at least one hydrocracking section ( 2 ),
(e) a section for rectifying a second portion ( 20 ) of the first residue ( 15 ) obtained in the fractionating zone, comprising at least one column ( 21 ), at a pressure P2 at the top thereof which is at least 0.05 MPa lower than the pressure P1, to obtain at least a secondary distillate ( 23 ), a secondary residue ( 16 ) and a vapor stream ( 22 ),
(f) a section for purging at least one portion, or all, of the secondary residue ( 16 ), and
(g) a line for recycling all or part of said secondary distillate ( 23 ) to the hydrocracking section ( 2 ) or at least one of the hydrocracking sections, after an optional gas separation section,
wherein said plant is free of a line for recycling all or part of the of the overhead vapor stream ( 22 ) resulting from the rectifying step (e).

20. The plant according to claim 19 , wherein said plant is free of a line for recycling all or part of the secondary distillate ( 23 ) and/or all or part of the secondary residue ( 16 ) which result from the rectifying zone (e) to the fractionating zone (c).

21. The plant according to claim 19 , wherein the rectifying zone (e) is equipped with pressure control devices, either of pressure regulator type if the pressure P2 is greater than atmospheric pressure, or of vacuum device type if the pressure P2 is lower than atmospheric pressure.

22. The plant according to claim 19 , further comprising:
one or two hydrocracking section(s) ( 2 ) equipped with a feedstock inlet line ( 1 ) and a hydrogen inlet line ( 8 ),
the fractionating section ( 12 ) comprising at least one distillation column equipped with

Assignees

• Axens

Inventors

• Bonnardot Jerome
• Dulot Hugues
• Paillier Alexis
• Pigourier Jerome
• Pupat Nicolas

Classifications

• C10G67/02 Primary

  plural serial stages only · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title

• B01D3/346

  the gas being used for removing vapours, e.g. transport gas · CPC title

• B01D3/42

  Regulation; Control · CPC title

• B01J19/0006

  Controlling or regulating processes (controlling or regulating in general G05) · CPC title