Heavy hydrocarbon removal from lean gas to lng liquefaction

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 C5+ 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 C5+ 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.

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 stream, 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, wherein the physical solvent unit further comprises a wash section configured for contacting the feed gas stream with water;   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 , further comprising a mercury removal unit configured to remove mercury in the treated gas. 
     
     
         4 . 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. 
     
     
         5 . The system of  claim 1 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a C 5+  composition below about 0.1% by volume. 
     
     
         6 . The system of  claim 1 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a C 6+  composition below about 150 ppmv. 
     
     
         7 . 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. 
     
     
         8 . 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 stream. 
     
     
         9 . The system of  claim 1 , further comprising feed gas in the feed gas stream, wherein the feed gas has a C 3+  composition below about 2 to 3 GPM. 
     
     
         10 . The system of  claim 1 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a water composition at or below about 1 lb/MMscf. 
     
     
         11 . The system of  claim 1 , wherein the physical solvent unit is configured to contact the feed gas stream with the physical solvent and then with the water. 
     
     
         12 . 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, wherein the feed gas stream comprises C 1  hydrocarbons, C 2  hydrocarbons, C 3  hydrocarbons, C 4  hydrocarbons, C 5+  hydrocarbons, and/or acid gas components, remove at least a portion of any acid gases present in the feed gas stream, and produce a cleaned gas stream, wherein the cleaned gas stream comprises C 1  hydrocarbons, C 2  hydrocarbons, C 3  hydrocarbons, C 4  hydrocarbons, and/or C 5+  hydrocarbons;   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, wherein the physical solvent unit further comprises a wash section configured for contacting the cleaned gas stream with water; 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.   
     
     
         13 . The system of  claim 12 , wherein the physical solvent unit is configured to contact the cleaned gas stream with a physical solvent and then with the water. 
     
     
         14 . The system of  claim 12 , 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.   
     
     
         15 . The system of  claim 12 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a benzene, toluene, and xylene composition below about 1 ppmv. 
     
     
         16 . The system of  claim 12 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a C 5+  composition below about 0.1% by volume. 
     
     
         17 . The system of  claim 12 , wherein the physical solvent unit is configured to produce the cleaned gas stream having a C 6+  composition below about 150 ppmv. 
     
     
         18 . The system of  claim 12 , 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. 
     
     
         19 . The system of  claim 12 , further comprising the feed gas, wherein the feed gas has a C 2 + composition below about 2 to 3 GPM. 
     
     
         20 . The system of  claim 12 , wherein the physical solvent unit is configured to remove at least a portion of any water present in the feed gas; and/or wherein the physical solvent unit is configured to produce the cleaned gas stream having a water composition at or below about 1 lb/MMscf.