Apparatus and system for swing adsorption processes related thereto

• US 10,080,992 B2
• Filed: 08/10/2016
• Issued: 09/25/2018
• Est. Priority Date: 09/02/2015
• Status: Active Grant

• Current Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Original Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Inventors: Nagavarapu, Ananda K., Smith, Ransdall K., Oelfke, Russell H.
• Primary Examiner(s): Lawrence, Jr., Frank M
• Application Number:
  US15/233,640
• Publication Number:
  US 20170056815A1
• Time in Patent Office: 776 Days
• Field of Search: 95 96- 98, 95100, 95104, 95105, 95117, 95122, 95139, 96108, 96121, 96132, 96134, 62618, 62620
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/116 Molecular sieves other than zeolites
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/40 Nitrogen compounds
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/40013 Pressurization
• CPC Class Codes: B01D 2259/40043 Purging
• CPC Class Codes: B01D 2259/40054 treated before its reuse
• CPC Class Codes: B01D 2259/40086 by using a purge gas B01D2259/4009 takes precedence
• CPC Class Codes: B01D 2259/4009 using hot gas
• CPC Class Codes: B01D 2259/4062 using six beds
• CPC Class Codes: B01D 2259/416 involving cryogenic temperature treatment
• CPC Class Codes: B01D 53/0407 Constructional details of adsorbing systems
• CPC Class Codes: B01D 53/0462 Temperature swing adsorption
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: B01D 53/0473 Rapid pressure swing adsorption
• CPC Class Codes: C10L 2290/543 Distillation, fractionation or rectification for separating fractions, components or impurities during preparation or upgrading of a fuel
• CPC Class Codes: C10L 3/104 : Carbon dioxide
• CPC Class Codes: C10L 3/106 : of water
• CPC Class Codes: F25J 2200/02 : in a single pressure main column system
• CPC Class Codes: F25J 2200/40 : Features relating to the provision of boil-up in the bottom of a column
• CPC Class Codes: F25J 2200/70 : Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2205/04 : in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2205/64 : by pressure-swing adsorption [PSA] at the hot end
• CPC Class Codes: F25J 2205/66 : Regenerating the adsorption vessel, e.g. kind of reactivation gas
• CPC Class Codes: F25J 2220/66 : Separating acid gases, e.g. CO2, SO2, H2S or RSH
• CPC Class Codes: F25J 2220/68 : Separating water or hydrates
• CPC Class Codes: F25J 2230/32 : Compression of the product stream
• CPC Class Codes: F25J 2230/60 : the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2240/02 : Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 3/0209 : Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0233 : separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 : separation of CnHm with 2 carbon atoms or more
• CPC Class Codes: F25J 3/061 : Natural gas or substitute natural gas
• CPC Class Codes: Y02C 20/40 : of CO2

Abstract

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve passing streams through adsorbent bed units to treat the feed stream to form a stream that complies with nitrogen rejection specifications. The process may involve using at least a portion of the nitrogen rejection process product streams as a purge for the swing adsorption process.

Claims

1. A process for removing contaminants from a gaseous feed stream, the process comprising:

a. performing one or more adsorption steps, wherein each of the one or more adsorption steps comprise passing a gaseous feed stream through an adsorbent bed unit having an adsorbent bed to separate one or more contaminants from the gaseous feed stream to form a product stream that is conducted away to a nitrogen rejection unit configured to form a methane stream and a nitrogen stream;

b. performing one or more depressurization steps, wherein the pressure within the adsorbent bed unit is reduced by a predetermined amount with each successive depressurization step;

c. performing a purge step, wherein the purge step comprises passing a first purge stream into the adsorbent bed unit, wherein the purge stream is passed in a countercurrent direction relative to the direction of the feed stream and wherein the first purge stream comprises at least a portion of the methane stream; and

d. repeating the steps a) to c) for at least one additional cycle, wherein the cycle duration is for a period greater than 1 second and less than 600 seconds.

2. The process of claim 1, wherein the first purge stream further comprises at least a portion of the nitrogen stream.

3. The process of claim 1, further comprising performing a second purge step, wherein the second purge step comprises passing a second purge stream into the adsorbent bed unit, wherein the second purge stream is passed in a countercurrent direction relative to the direction of the feed stream and wherein the second purge stream comprises one of at least a portion of the methane stream, at least a portion of the nitrogen stream, and any combination thereof.

4. The process of claim 3, wherein the second purge stream comprises at least a portion of the nitrogen stream.

5. The process of claim 1, wherein the gaseous feed stream is a hydrocarbon containing stream having greater than one volume percent hydrocarbons based on the total volume of the gaseous feed stream.

6. The process of claim 1, wherein the adsorbent bed unit is configured to lower the carbon dioxide (CO₂) level to less than 30 parts per million.

7. The process of claim 1, wherein the gaseous feed stream is provided at a feed pressure in the range between 50 bar absolute (bara) and 150 bara and at a feed temperature in the range between 0°

F. and 200°

F.

8. The process of claim 1, wherein performing one or more adsorption steps further comprises passing the gaseous feed stream to a molecular sieve unit configured to conduct away a portion of the H₂O in the gaseous feed stream and to pass the gaseous feed stream to the adsorbent bed unit.

9. The process of claim 1, wherein performing one or more adsorption steps further comprises passing the gaseous feed stream to a dehydration adsorbent bed unit configured to conduct away a portion of the H₂O in the gaseous feed stream and to pass the gaseous feed stream to the adsorbent bed unit.

10. The process of claim 9, wherein the dehydration adsorbent bed unit is configured to:

a) perform one or more adsorption steps, wherein each of the one or more adsorption steps comprise passing the gaseous feed stream through the dehydration adsorbent bed unit having a dehydration adsorbent bed to separate H₂O from the gaseous feed stream;

b) perform one or more depressurization steps, wherein the pressure within the dehydration adsorbent bed unit is reduced by a predetermined amount with each successive depressurization step;

c) perform a purge step, wherein the purge step comprises passing a dehydration purge stream into the dehydration adsorbent bed unit, wherein the dehydration purge stream is passed in a countercurrent direction relative to the direction of the gaseous feed stream and wherein the dehydration purge stream comprises one of at least a portion of the methane stream, at least a portion of the nitrogen stream, and any combination thereof; and

d) repeat the steps a) to c) for at least one additional cycle, wherein the cycle duration is for a period greater than 1 second and less than 600 seconds.

11. The process of claim 10, wherein the dehydration purge stream comprises at least a portion of the nitrogen stream.

12. The process of claim 1, further comprising compressing the one of at least a portion of the methane stream, at least a portion of the nitrogen stream, and any combination thereof prior to passing the purge stream into the adsorbent bed unit.

13. The process of claim 1, wherein the cycle duration is greater than 2 seconds and less than 180 seconds.

14. A system for removing contaminants from a gaseous feed stream, the system comprising:

an adsorbent bed unit configured to separate contaminants from a gaseous feed stream and to output a product stream, wherein the adsorbent bed unit comprises an adsorbent bed and the adsorbent bed unit is configured to perform a rapid cycle swing adsorption process;

a nitrogen rejection unit in fluid communication with the adsorbent bed unit and configured to receive the product stream and separate the product stream into a methane stream and a nitrogen stream; and

wherein the adsorbent bed unit is configured to pass a first purge stream through the adsorbent bed, wherein the first purge stream is passed in a countercurrent direction relative to the direction of the feed stream and wherein the purge stream comprises at least a portion of the methane stream.

15. The system of claim 14, further comprising a dehydration adsorption unit in fluid communication with the adsorbent bed unit and configured to conduct away H₂O from the gaseous feed stream and pass the gaseous feed stream to the adsorbent bed unit.

16. The system of claim 15, wherein the dehydration adsorption unit is a molecular sieve adsorption unit.

17. The system of claim 15, wherein the dehydration adsorption unit is a dehydration adsorbent bed unit configured to perform a rapid cycle swing adsorption process.

18. The system of claim 17, wherein the dehydration adsorbent bed unit is configured to pass a dehydration purge stream into the dehydration adsorbent bed unit, wherein the dehydration purge stream is passed in a countercurrent direction relative to the direction of the gaseous feed stream and wherein the dehydration purge stream comprises at least a portion of the methane stream.

19. The system of claim 14, wherein the adsorbent bed unit is configured to lower the carbon dioxide (CO₂) level to less than 30 parts per million molar.

20. The system of claim 14, wherein the adsorbent bed unit is configured to lower the water (H₂O) level to less than 0.1 parts per million molar.

21. The system of claim 14, wherein the first purge stream further comprises at least a portion of the nitrogen stream.

22. The system of claim 18, wherein the dehydration purge stream further comprises at least a portion of the nitrogen stream.