Processes and systems for refining fuel gas

Patent metadata

Field	Value
Publication number	US-2016115409-A1
Application number	US-201414520939-A
Country	US
Kind code	A1
Filing date	Oct 22, 2014
Priority date	Oct 22, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

Processes and systems are provided for refining fuel gas. The processes involve first and second water wash stages, before and after a caustic wash stage, in which fuel gas is contacted with water for removing amine and caustic compounds from the fuel gas. The systems for refining LPG comprise a first water wash vessel and a caustic wash vessel, followed by a second water wash vessel, wherein the water wash vessels are each adapted for contacting the LPG with water to remove amine and caustic compounds therefrom.

First claim

What is claimed is:

1 . A process for refining fuel gas comprising:
providing a fuel gas comprising an amine compound; contacting the fuel gas with water in a first water wash stage to remove at least a portion of the amine compound therefrom and produce a washed fuel gas; contacting the washed fuel gas with either a caustic to remove acid gas or a blend of a caustic and an amine to remove both acid gas and carbonyl sulfide (COS) from the washed fuel gas and produce a caustic treated fuel gas comprising residual amine and residual caustic; and contacting the caustic treated fuel gas with water in a second water wash stage to remove residual amines and residual caustic therefrom and produce a rewashed fuel gas substantially free of amine and caustic.

2 . The process of claim 1 , wherein contacting the fuel gas with water in a first water wash stage further comprises using a coalescing material.

3 . The process of claim 1 , wherein contacting the caustic treated fuel gas with water in a second water wash stage further comprises using a coalescing material, which may be the same or different from the coalescing material used in the first water wash stage.

4 . The process of claim 1 , wherein providing the fuel gas comprises contacting a fuel gas with an amine compound to remove hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), or both, therefrom and produce an amine treated fuel gas comprising an amine compound, and wherein the amine treated fuel gas is then contacted with water.

5 . The process of claim 4 , wherein contacting the fuel gas with an amine compound is performed by absorption with an aqueous solution comprising the amine compound.

6 . The process of claim 4 , wherein providing the fuel gas comprises providing liquefied petroleum gas (LPG).

7 . The process of claim 1 , wherein contacting the washed fuel gas with caustic is performed using a strong base selected from sodium hydroxide and potassium hydroxide as the caustic.

8 . The process of claim 1 , wherein a single vessel is used for contacting the fuel gas with water to produce the washed fuel gas, and for contacting the washed fuel gas with a caustic to produce the caustic treated fuel gas comprising residual amine and residual caustic, and for contacting the caustic treated fuel gas with water in a second water wash stage to the rewashed fuel gas substantially free of amine and caustic.

9 . The process of claim 8 , wherein the fuel gas is chosen from: methane, ethane, propane, isobutene and mixtures thereof.

10 . The process of claim 1 , further comprising removing mercaptans from the rewashed fuel gas.

11 . The process of claim 10 , wherein removing mercaptans from the rewashed fuel gas comprises contacting the rewashed fuel gas with an aqueous caustic solution in the presence of a catalyst to produce a refined fuel gas product and an aqueous solution comprising mercaptan derivatives; and heating and oxidizing the aqueous solution comprising mercaptan derivatives to convert the mercaptan derivatives to disulfides and regenerated caustic.

12 . A process for refining fuel gas comprising:
contacting a fuel gas with an amine compound to remove hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), or both therefrom and produce an amine treated fuel gas comprising an amine compound; contacting the amine treated fuel gas with water to remove at least a portion of the amine compound therefrom and produce a washed fuel gas; contacting the washed fuel gas with a either a caustic to remove acid gas or a blend of a caustic and an amine to remove both acid gas and carbonyl sulfide (COS) from the washed fuel gas and produce a caustic treated fuel gas comprising residual amine and residual caustic; contacting the caustic treated fuel gas with water to remove residual amines and residual caustic therefrom and produce a rewashed fuel gas substantially free of amine and caustic; and removing mercaptans from the rewashed fuel gas.

13 . The process of claim 12 , wherein contacting the fuel gas with water in a first water wash stage further comprises contacting the fuel gas and water with a coalescing material.

14 . The process of claim 12 , wherein contacting the caustic treated fuel gas with water in a second water wash stage further comprises contacting the caustic treated fuel gas with a coalescing material, which may be the same or different from the coalescing material in the first water wash stage.

15 . The process of claim 12 , wherein contacting a fuel gas with an amine compound to remove hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), or both therefrom comprises selecting and using, as the amine, one or more compounds chosen from: monoethanolamine, diethanolamine, diglycolamine, methyl diethanolamine (MDEA), MDEA-based solvents, and diisopropylamine.

16 . A system for refining liquefied petroleum gas (LPG) comprising:
a first water wash vessel; a caustic wash vessel in fluid communication with, and located downstream of, the first water wash vessel; and a second water wash vessel in fluid communication with, and located downstream of, the caustic wash vessel.

17 . The system of claim 16 , wherein the first water wash vessel comprises an interior and a coalescing material positioned within the interior.

18 . The system of claim 16 , wherein the second water wash vessel comprises an interior and a coalescing material positioned within the interior, wherein the coalescing material may be the same or different from the coalescing material of the first water wash vessel.

19 . The system of claim 16 , further comprising an absorber wherein the first water wash vessel is in fluid communication with, and located downstream of, the absorber.

20 . The system of claim 16 , further comprising mercaptan removal apparatus.

Assignees

• Uop Llc

Inventors

• Laricchia Luigi
• Trucko Jessy E

Classifications

• C10L2290/541

  Absorption of impurities during preparation or upgrading of a fuel · CPC title

• C10L3/12 Primary

  Liquefied petroleum gas {(liquefying by pressure and cold treatment F25J)} · CPC title

• C10L2290/545

  Washing, scrubbing, stripping, scavenging for separating fractions, components or impurities during preparation or upgrading of a fuel · CPC title

• C10L2290/56

  Specific details of the apparatus for preparation or upgrading of a fuel · CPC title

• C10L3/103

  Sulfur containing contaminants · CPC title