System and method to remove organic acid from a rich MEG stream by stripping

Patent metadata

Field	Value
Publication number	US-10144686-B2
Application number	US-201715675260-A
Country	US
Kind code	B2
Filing date	Aug 11, 2017
Priority date	Apr 1, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A system and method for removing acetic acid and other short chain fatty acids described as organic acid from a rich mono-ethylene glycol (“MEG”) solution does so by stripping the organic acid from the rich MEG solution by contacting the solution with a gas, the gas being nitrogen or a fuel gas such as methane; and stripping the organic acid from the gas by contacting the gas with a caustic solution such as a dilute sodium hydroxide solution. The stripping steps take place in respective stripping columns. A portion of the gas exiting the gas/organic acid stripping column can be recycled to the MEG/organic acid stripping column to reduce total gas usage. A portion of the waste stream exiting the gas/organic acid stripping column can be recycled back to the gas/organic acid stripping column to reduce the amount of caustic solution used as well as the amount of waste.

First claim

What is claimed:

1. A method for removing organic acid from a MEG stream, the method comprising:
stripping the organic acid from the MEG stream after a hydrate inhibition use of the MEG stream by contacting the MEG stream with a gas
wherein the MEG stream after the contact with the gas is substantially free of the organic acid.

2. A method according to claim 1 further comprising:
washing the organic acid contained in the gas that contacted the MEG stream by contacting the gas with a caustic solution
wherein the gas after the contact with the caustic solution is substantially free of the organic acid.

3. A method according to claim 2 further comprising recycling a portion of the gas for use in the stripping of the organic acid from the MEG stream.

4. A method according to claim 2 further comprising recycling a portion of a waste stream from the washing of the organic acid contained in the gas for use in the washing of the organic acid contained in the gas.

5. A method according to claim 2 wherein the caustic solution is a sodium hydroxide solution comprising about 1% sodium hydroxide.

6. A method according to claim 1 further comprising adjusting, when needed, a pH of the MEG stream to a pH<4.

7. A method for removing organic acid from a MEG stream, the method comprising the steps of:
stripping the organic acid from the MEG stream after a hydrate inhibition use of the MEG stream by contacting the MEG stream with a gas wherein the MEG stream after the contact with the gas is substantially free of the organic acid; and
washing the organic acid contained in the gas that contacted the MEG stream by contacting the gas with a caustic solution, wherein the gas after contact by the caustic solution is substantially free of the organic acid.

8. A method according to claim 7 wherein the organic acid is a carboxylic acid.

9. A method according to claim 7 further comprising recycling a portion of the gas for use in the stripping of the organic acid from the MEG stream.

10. A method according to claim 7 further comprising recycling a portion of a waste stream from the washing of the organic acid contained in the gas for use in the washing of the organic acid contained in the gas.

11. A method according to claim 7 wherein the caustic solution is a sodium hydroxide solution comprising about 1% sodium hydroxide.

12. A method according to claim 7 further comprising the step of adjusting, when needed, a pH of the MEG stream to a pH<4.

13. A MEG reclamation and regeneration system the system comprising
a MEG/organic acid stripping column; and
a gas/organic acid washing column;

the MEG/organic acid stripping column configured to receive a stripping gas and a MEG stream containing the organic acid, the MEG stream exiting the MEG/organic stripping column as a substantially organic acid-free rich MEG stream; the stripping gas including the organic acid exiting the MEG/organic stripping column; and
the gas/organic acid washing column configured to receive a caustic solution and the stripping gas including the organic acid exiting the MEG/organic stripping column, the gas exiting the gas/organic washing column as a substantially organic acid free gas stream.

14. A system according to claim 13 further comprising a recycle loop, the recycle loop configured to receive a portion of the substantially organic acid gas free stream exiting the gas/organic acid washing column and route the portion back to the MEG/organic stripping column.

15. A system according to claim 13 further comprising a recycle loop, the recycle loop configured to receive a portion of a waste stream exiting the gas/organic acid washing column and route the portion back to the gas/organic acid washing column.

16. A system according to claim 13 , the stripping gas being nitrogen.

17. A system according to claim 13 , the stripping gas being methane.

18. A MEG regeneration and reclamation system comprising:
a MEG/organic acid stripping column; and
a gas/organic acid washing column;
the MEG/organic acid stripping column configured to receive a stripping gas and a MEG stream containing an organic acid;
the MEG stream exiting the MEG/organic stripping column as a substantially organic acid-free MEG stream;

the gas/organic acid washing column arranged to receive a caustic solution and the stripping gas containing the organic acid exiting the MEG/organic stripping column,
the stripping gas exiting the gas/organic washing column as a substantially organic acid-free gas stream;

wherein a pH of the MEG stream is less than 4; and
wherein the stripping gas is selected from the group consisting of nitrogen and methane.

19. A system according to claim 18 , the stripping gas being selected from a group consisting of nitrogen and methane.

20. A system according to claim 18 further comprising a first and a second recycle loop,
the first recycle loop configured to receive a portion of the substantially organic acid gas free stream exiting the gas/organic acid washing column and route the portion back to the MEG/organic stripping column;
the second recycle loop configured to receive a portion of a waste stream exiting the gas/organic acid washing column and route the portion back to the gas/organic acid washing column.

Assignees

• Cameron Solutions Inc

Inventors

• Langley Steven
• Knight David John

Classifications

• B01D53/78

  with gas-liquid contact · CPC title

• C07C51/412

  by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part · CPC title

• C10L3/107

  Limiting or prohibiting hydrate formation · CPC title

• B01D3/343

  the substance being a gas · CPC title

• C07C29/76 Primary

  by physical treatment · CPC title