Simplified LNG Process

• US 20130180282A1
• Filed: 01/12/2012
• Published: 07/18/2013
• Est. Priority Date: 01/12/2012
• Status: Active Grant

• Current Assignee: 9052151 Canada Corporation
• Original Assignee: 9052151 Canada Corporation
• Inventors: Palmer, Gary
• Granted Patent: US 9,612,050 B2
• Time in Patent Office: Days
• US Class Current: 62/611
• CPC Class Codes: F25J 1/0022 Hydrocarbons, e.g. natural gas
• CPC Class Codes: F25J 1/004 by flash gas recovery F25J1/0267 takes precedence
• CPC Class Codes: F25J 1/0208 in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop F25J1/021 takes precedence
• CPC Class Codes: F25J 1/0232 integration within a pressure letdown station of a high pressure pipeline system
• CPC Class Codes: F25J 1/0254 controlling particular process parameter, e.g. pressure, temperature
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2220/62 Separating low boiling components, e.g. He, H2, N2, Air
• CPC Class Codes: F25J 2220/64 Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
• CPC Class Codes: F25J 2220/66 Separating acid gases, e.g. CO2, SO2, H2S or RSH
• CPC Class Codes: F25J 2230/30 Compression of the feed stream
• CPC Class Codes: F25J 2240/40 Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
• CPC Class Codes: F25J 2245/90 the recycled stream being boil-off gas from storage
• CPC Class Codes: F25J 2270/90 External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
• CPC Class Codes: F25J 2290/62 Details of storing a fluid in a tank

Abstract

A simplified method for production of a commercial supply liquefied natural gas (LNG) supplied in a pressurized vessel includes taking a supply of natural gas including contaminants from a stranded well or from a pipe line and extracting from the supply gas water vapor and CO2 in a fixed bed absorption system. In a first stage the supply gas is separated into first and second streams where the first stream contains all the cold energy available from the feed stream and sufficient of the contaminants are removed to meet a product specification for the composition of the LNG supply. In a second stage the first stream is liquefied by the available cool energy for commercial pressurized supply container The second stream contains natural gas which is as much as 75% of the feed stream together with substantially all the contaminants and is used as a natural gas supply.

Claims

1. A method for production of liquefied natural gas (LNG) comprising:

taking a supply of natural gas including contaminants;

extracting from the supply gas water vapor and CO2;

in a first stage, separating the supply gas into first and second streams;

wherein the first stream is a cold stream arranged to have sufficient of the contaminants removed to meet a product specification for the composition of an LNG supply;

wherein the second stream contains natural gas and the contaminants;

and in a second stage liquefying the first stream for commercial supply;

and where in the second stream is returned for use as a natural gas supply.

2. The method according to claim 1 wherein the first stream is supplied as LNG.

3. The method according to claim 1 wherein the first stream is supplied in a container maintained under a pressure greater than atmosphere.

4. The method according to claim 1 wherein the first stream is supplied in a container stored at 100 PSIA (7 atmospheres).

5. The method according to claim 1 wherein any sulfur compounds are removed together with the CO2 and the water using a fixed bed adsorption system.

6. The method according to claim 1 wherein contaminants removed from the first stream and supplied in the second stream include N2, CO2, Ethane, Propane plus any other heavy components.

7. The method according to claim 1 wherein contaminants are removed from the first stream so as to make up less than approximately 1% of the first stream as the commercial supply.

8. The method according to claim 1 wherein the second stream is typically 70 to 75% of the feed stream.

9. The method according to claim 1 wherein the second stream is in the range 50 to 80% of the feed stream.

10. The method according to claim 1 wherein all the cool energy is extracted from the second stream.

11. The method according to claim 1 wherein the feed stream is taken from a natural gas pipeline and the second stream is returned to the pipeline along with the contaminants.

12. The method according to claim 1 wherein the feed stream is a stranded gas well and the second stream is consumed locally as a natural gas supply.

13. The method according to claim 1 wherein the feed supply is a pipe line and the method is used for peak shaving by tapping into the pipeline during periods of low demand to store gas for the time when demand peaks.