Liquefaction of natural gas with product used as absorber purge

Claim 2

A process according to claim 2, further comprising cooling at least a portion of the high pressure nitrogen feed stream in said refrigeration cycle with said hydrocarbons.

Claim 3

A process according to claim 2, wherein said hydrocarbons are used as fuel to drive a compressor in said refrigeration cycle.

Claim 4

A process according to claim 1, including venting said bleed stream following purging into a fuel gas stream for driving a compressor in said refrigeration cyclE.

Claim 5

A process according to claim 1 including withdrawing the boil-off from the LNG storage facility and condensing the same by heat exchange with liquid nitrogen from the refrigeration cycle, returning the condensed boil-off to the storage facility.

Claim 6

A process according to claim 6 wherein the condensed boil-off is joined by means of an eductor with the liquefied natural gas being directed to the storage facility.

Claim 7

A process according to claim 1 including sweetening the liquefied natural gas in the storage facility by introducing substantially pure methane into said facility.

Claim 8

A process for the production of substantially pure methane and liquefied natural gas from a feed stream of natural gas comprising the steps of: a. removing moisture and carbon dioxide from said feed stream; b. liquefying at least part of the hydrocarbons heavier than methane in a first cooling step; c. separating said at least part from said feed stream; d. liquefying said feed stream in a second cooling step; e. rectifying said liquefied feed stream to strip nitrogen and at least part of the methane therefrom; f. further rectifying said stripped nitrogen and methane to produce substantially pure nitrogen and substantially pure methane; g. further cooling the remainder of the liquefied feed stream in a first subcooling step and in a second subcooling step; h. expanding the subcooled feed stream and storing the same as LNG; i. compressing a refrigerant gas in a plurality of steps; j. splitting said compressed refrigerant gas into a major stream and a minor stream; k. cooling said major stream in said first cooling step, said second cooling step, and said first subcooling step; l. dividing said major stream into two further streams, liquefying one of said further streams in said second subcooling step, work expanding the other of said streams and passing the resulting cold gas through said second and first subcooling steps and returning said gas to be compressed; m. cooling at least part of said minor stream by heat exchange with the liquefied hydrocarbons produced in steps (b) and (c); n. expanding said minor stream, combining it with the substantially pure nitrogen from step (f) and passing the combined streams through said second cooling step to provide at least part of the refrigeration therefore; and o. further expanding the warmed minor stream, combining the expanded minor stream with the other of said streams of step (l) and passing the so-combined streams through said second cooling step and first cooling step to provide at least part of the refrigeration therefore.

Claim 9

A process according to claim 9, including cooling at least part of said minor stream with a Freon refrigeration cycle, combining said at least part with the part cooled in step (m).

Claim 10

A process according to claim 9, including subcooling the substantially pure methane produced in step (f) in the first and second subcooling steps and directing the same to a methane storage facility.

Claim 11

A process according to claim 1, including sweetening the stored LNG referred to in step (h) by injecting substantially pure methane into said LNG.

Claim 12

A process according to claim 9 including condensing the boil-off from the stored LNG by heat exchange with the liquefied further stream referred to in step (l), returning the condensed boil-off to the stored LNG.