Heavy hydrocarbon removal from lean gas to lng liquefaction

Patent metadata

Field	Value
Publication number	US-2018017319-A1
Application number	US-201615209015-A
Country	US
Kind code	A1
Filing date	Jul 13, 2016
Priority date	Jul 13, 2016
Publication date	Jan 18, 2018
Grant date	—

Abstract

A system for processing a gas stream can include a physical solvent unit, an acid gas removal unit upstream or downstream of the physical solvent unit, and an LNG liquefaction unit downstream of the acid gas removal unit. The physical solvent unit is configured to receive a feed gas, remove at least a portion of any C 5+ hydrocarbons in the feed gas stream using a physical solvent, and produce a cleaned gas stream comprising the feed gas stream with the portion of the C 5+ hydrocarbons removed. The acid gas removal unit is configured to receive the cleaned gas stream, remove at least a portion of any acid gases present in the cleaned gas stream, and produce a treated gas stream. The LNG liquefaction unit is configured to receive the treated gas stream and liquefy at least a portion of the hydrocarbons in the treated gas stream.

First claim

What is claimed is:

1 . A system for processing a gas stream, the system comprising:
a physical solvent unit, wherein the physical solvent unit is configured to receive a feed gas, remove at least a portion of any C 5+ hydrocarbons in a feed gas stream using a physical solvent, and produce a cleaned gas stream comprising the feed gas stream with the portion of the C 5+ hydrocarbons removed; an acid gas removal unit downstream of the physical solvent unit, wherein the acid gas removal unit is configured to receive the cleaned gas stream, remove at least a portion of any acid gases present in the cleaned gas stream, and produce a treated gas stream; and an LNG liquefaction unit downstream of the acid gas removal unit, wherein the LNG liquefaction unit is configured to receive the treated gas stream and liquefy at least a portion of the hydrocarbons in the treated gas stream.

2 . The system of claim 1 , further comprising:
a dehydration unit downstream of the acid gas removal unit and upstream of the LNG liquefaction unit, wherein the dehydration unit is configured to remove at least a portion of the water present in the treated gas stream prior to the treated gas stream passing to the LNG liquefaction unit.

3 . The system of claim 1 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a benzene, toluene, and xylene composition below about 1 ppmv.

4 . The system of claim 1 , further comprising the physical solvent, wherein the physical solvent comprises dimethylether of polyethylene glycol, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, glycol ethers, ethers of polyglycols, N-substituted morpholine, or any combination thereof.

5 . The system of claim 1 , wherein the physical solvent unit is configured to remove at least a portion of any water present in the feed gas.

6 . A system for processing a gas stream, the system comprising:
an acid gas removal unit, wherein the acid gas removal unit is configured to receive a feed gas stream, remove at least a portion of any acid gases present in the feed gas stream, and produce a cleaned gas stream; a physical solvent unit downstream of the acid gas removal unit, wherein the physical solvent unit is configured to receive the cleaned gas stream, remove at least a portion of any C 5+ hydrocarbons in the cleaned gas stream, and produce a treated gas stream comprising the cleaned gas stream with the portion of the C 5+ hydrocarbons removed; and an LNG liquefaction unit downstream of the physical solvent unit, wherein the LNG liquefaction unit is configured to receive the treated gas stream and liquefy at least a portion of the hydrocarbons in the treated gas stream.

7 . The system of claim 6 , further comprising:
a dehydration unit downstream of the acid gas removal unit and upstream of the LNG liquefaction unit, wherein the dehydration unit is configured to receive the treated gas stream and remove at least a portion of the water present in the treated gas stream prior to the cleaned gas stream passing to the LNG liquefaction unit.

8 . The system of claim 6 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a benzene, toluene, and xylene composition below about 1 ppmv.

9 . The system of claim 6 , further comprising a physical solvent disposed in the physical solvent unit, wherein the physical solvent comprises dimethylether of polyethylene glycol, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, glycol ethers, ethers of polyglycols, N-substituted morpholine, or any combination thereof.

10 . A method of processing a gas stream, the method comprising:
contacting a gas stream with a physical solvent, wherein the gas stream comprises C 1 hydrocarbons, C 2 hydrocarbons, C 3 hydrocarbons, C 4 hydrocarbons, C 5+ hydrocarbons, and acid gas components; removing at least a portion of the C 3+ hydrocarbons based on the contacting with the physical solvent; contacting the gas stream with a solvent; removing at least a portion of the acid gas components based on the contacting with the physical solvent; and liquefying at least a portion of the gas stream after contacting the gas stream with the physical solvent and the solvent.

11 . The method of claim 10 , wherein the gas stream further comprises water, and wherein the method further comprises:
removing at least a portion of the water in the gas stream prior to liquefying at least the portion of the gas stream.

12 . The method of claim 11 , wherein removing at least the portion of the water in the gas stream occurs in response to contacting the gas stream with the physical solvent.

13 . The method of claim 12 , wherein removing at least the portion of the water in the gas stream reduces the water in the gas stream to at or below about 1 lb/MMscf.

14 . The method of claim 11 , wherein removing at least the portion of the water in the gas stream occurs in a dehydration unit.

15 . The method of claim 10 , wherein the physical solvent comprises dimethylether of polyethylene glycol, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, glycol ethers, ethers of polyglycols, N-substituted morpholine, or any combination thereof.

16 . The method of claim 10 , wherein contacting the gas stream with the physical solvent and contacting the gas stream with the solvent occurs at a pressure between about 900 psig and about 1500 psig.

17 . The method of claim 10 , wherein contacting the gas stream with the physical solvent removes between about 20% and about 40% of the C 5 hydrocarbons in the gas stream being contacted with the physical solvent.

18 . The method of claim 10 , wherein contacting the gas stream with the physical solvent removes between about 30% and 70% of the C 6 hydrocarbons in the gas stream being contacted with the physical solvent.

19 . The method of claim 10 , wherein contacting the gas stream with the physical solvent removes between about 90% and 95% of the C 7 , hydrocarbons in the gas stream being contacted with the physical solvent.

20 . The method of claim 10 , wherein contacting the gas stream with the physical solvent removes greater than 90% of the aromatic hydrocarbons in the gas stream being contacted with the physical solvent.

Assignees

• Fluor Tech Corp

Inventors

• Mak John
• Thomas Jacob

Classifications

• B01D53/263

  by absorption · CPC title

• B01D2252/20468

  containing a pyrrolidone-ring · CPC title

• B01D2257/602

  Mercury or mercury compounds · CPC title

• F25J1/0022 Primary

  Hydrocarbons, e.g. natural gas · CPC title

• C10L2290/541

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