Enriched acid gas for sulfur recovery

Patent metadata

Field	Value
Publication number	US-10597297-B2
Application number	US-201916598775-A
Country	US
Kind code	B2
Filing date	Oct 10, 2019
Priority date	Aug 18, 2017
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

A system of enriching acid gas for feeding a sulfur recovery unit includes a contactor configured to separate an acid gas stream into a carbon dioxide rich stream and a purified acid gas stream, where the acid gas stream includes hydrogen sulfide, carbon dioxide, and hydrocarbons; a regenerator in fluid communication with the contactor such that the regenerator is configured to separate the purified acid gas stream to create a hydrogen sulfide rich stream and a hydrogen sulfide lean stream; and a recycle stream conduit fluidly coupled between the regenerator to the contactor and configured to supply at least a portion of the hydrogen sulfide rich stream from the regenerator to the contactor.

First claim

The invention claimed is:

1. A system of acid gas enrichment, the system comprising:
an acid gas stream connector configured to receive an acid gas stream;
a contactor configured to separate the acid gas stream received from the acid gas stream connector into a carbon dioxide rich stream and a purified acid gas stream, the acid gas stream comprising hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), and hydrocarbons;
a regenerator in fluid communication with the contactor such that the regenerator is configured to separate the purified acid gas stream to obtain a hydrogen sulfide rich stream and a hydrogen sulfide lean stream, the hydrogen sulfide rich stream having a concentration of hydrogen sulfide;
a recycle stream conduit fluidly coupled between the regenerator and the contactor, and configured to supply at least a portion of the hydrogen sulfide rich stream from the regenerator to the contactor; and
an acid gas recycle valve coupled to the recycle stream conduit that opens and closes a fluid pathway from the regenerator to the contactor based on an H 2 S content in the hydrogen sulfide rich stream to direct the hydrogen sulfide rich stream exiting the regenerator to combine with the acid gas stream at the acid gas stream connector prior to the combination of the hydrogen sulfide rich stream and the acid gas stream entering the contactor.

2. The system of claim 1 , wherein the system comprises a single contactor.

3. The system of claim 1 , wherein the system is exclusive of a vacuum spool or a compressor for the contactor.

4. A system of acid gas enrichment, the system comprising:
an acid gas stream connector configured to receive an acid gas stream;
a contactor connected to the acid gas stream connector by a conduit, the contactor configured to separate the acid gas stream from the acid gas stream connector into a carbon dioxide rich stream and a purified acid gas stream, the acid gas stream comprising hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), and hydrocarbons;
a regenerator in fluid communication with the contactor, the regenerator configured to separate the purified acid gas stream to obtain a hydrogen sulfide rich stream and a hydrogen sulfide lean stream, the hydrogen sulfide rich stream having a concentration of hydrogen sulfide;
a recycle valve positioned in another conduit between the regenerator and the acid gas stream connector to direct the hydrogen sulfide rich stream exiting the regenerator to combine with the acid gas stream at the acid gas stream connector prior to the combination of the hydrogen sulfide rich stream and the acid gas stream entering the contactor; and
a controller configured to operate the recycle valve based on an H 2 S content in the hydrogen sulfide rich stream, wherein the recycle valve, when in an open state, is configured to separate at least a portion of the hydrogen sulfide rich stream exiting from the regenerator and to feed the portion of the hydrogen sulfide rich stream to the contactor, and wherein the recycle valve, when in an closed state, is configured to purge an entire hydrogen sulfide rich stream exiting from the regenerator.

5. The system of claim 4 , wherein the controller is configured to open, partially open, or close the recycle valve.

6. The system of claim 4 , wherein the controller is configured to open the recycle valve when the H 2 S content in the hydrogen sulfide rich stream is less than 35% wt.

7. The system of claim 4 , wherein the controller is configured to close the recycle valve when the H 2 S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt.

8. The system of claim 4 , wherein the controller is configured to close the recycle valve when an H 2 S content in the carbon dioxide rich stream is greater than or equal to 500 ppm.

9. The system of claim 4 , wherein the controller is configured to close the recycle valve when a total mass flow of the recycled hydrogen sulfide rich stream from the regenerator is 20% wt. or greater than the acid gas stream to the contactor.

10. The system of claim 1 , wherein the acid gas recycle valve is configured to open when the H 2 S content in the hydrogen sulfide rich stream is less than 35% wt.

11. The system of claim 1 , wherein the acid gas recycle valve is configured to open when the H 2 S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt.

12. The system of claim 1 , wherein the acid gas recycle valve is configured to open when an H 2 S content in the carbon dioxide rich stream is greater than or equal to 500 ppm.

13. The system of claim 1 , wherein the acid gas recycle valve is configured to close when at least one of:
the H 2 S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt;
a threshold mass flow of the recycled hydrogen sulfide rich stream from the regenerator is 20% wt or greater than a mass flow of the acid gas stream to the contactor; or
an H 2 S content in the carbon dioxide rich stream is at least 500 ppm.

14. The system of claim 1 , wherein the acid gas recycle valve is configured to close when:
the H 2 S content in the hydrogen sulfide rich stream is greater than or equal to 75% wt;
a threshold mass flow of the recycled hydrogen sulfide rich stream from the regenerator is 20% wt or greater than a mass flow of the acid gas stream to the contactor; and
an H 2 S content in the carbon dioxide rich stream is at least 500 ppm.

15. The system of claim 1 , wherein the acid gas recycle valve is configured to open or close based on an operating pressure of the contactor.

16. The system of claim 4 , wherein the controller is configured to determine a residual factor based on a flow rate of the hydrogen sulfide rich stream and a flow rate of the carbon dioxide rich stream.

17. The system of claim 16 , wherein the residual factor comprises a comparative measurement that compares flow rates of the hydrogen sulfide rich stream and the carbon dioxide rich stream in a predicted model to measured flow rates of the hydrogen sulfide rich stream and the carbon dioxide rich stream.

18. The system of claim 16 , wherein the controller is configured to:
(i) determine that the residual factor is within an acceptable level;
(ii) determine a measured flow rate of the hydrogen sulfide rich stream is outside of an acceptable level; and
(iii) based on the determinations in (i) and (ii), adjust the recycle value toward an open state or maintaining the recycle valve at the open state.

19. The system of claim 16 , wherein the controller is configured to:
(i) determine that the residual factor is within an acceptable level;
(ii) determine a measured flow rate of the hydrogen sulfide rich stream is within an acceptable level; and
(iii) based on the determinations in (i) and (ii), adjust the recycle value toward a closed state or maintaining the recycle valve at the closed state.

20. The system of claim 16 , wherein the controller is configured to open or close the recycle valve based on an operating pressure of the contactor.

Assignees

• Saudi Arabian Oil Co

Inventors

• Al-Qahtani Nasser A

Classifications

• B01D2252/20489

  with two or more hydroxyl groups · CPC title

• B01D53/1462

  Removing mixtures of hydrogen sulfide and carbon dioxide · CPC title

• B01D2252/20405

  Monoamines · CPC title

• B01D2252/20431

  Tertiary amines · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title