US 6,182,468 B2 · Thermodynamic separation of heavier components from natural gas

Abstract

A process for separation of particularly propane, methane or ethane from natural gas includes providing a distillation tower arrangement for separating the heavier components discharged at the bottom from lighter gas discharged at the top with at least two separate towers at different pressures such that the heavier product from the higher pressure tower is expanded and fed to the lower pressure tower. A feed gas containing the components under a first pressure is separated into a first proportion and a second proportion, where neither proportion is zero. The first proportion is fed to the tower. The second proportion is compressed to a pressure higher than the first pressure, heat is extracted from the compressed second proportion to effect condensation thereof, the compressed condensed second proportion is sub-cooled, expanded to the first pressure and supplied after expansion to the distillation tower arrangement at a position thereon adjacent the top of the distillation tower arrangement so as to cause cooling of the materials in the distillation tower arrangement. The method is particularly advantageous in a low pressure supply system in which the lighter gas discharged at the top of the tower arrangement is supplied at a pressure less than 100 psi and more preferably less than 75 psi.

Claims20

Dependent claims

A method of separating heavier components from natural gas comprising:

providing a distillation tower arrangement for separating the heavier components discharged at the bottom of the tower arrangement from lighter gas discharged at the top of the tower arrangement;
generating a residue gas stream from the lighter gas components for supply at a residue gas pressure to a downstream process;
providing a feed gas containing the components under a feed pressure;
separating the feed gas into a first proportion and a second proportion, where neither proportion is zero;
feeding the first proportion at the feed pressure to the distillation tower arrangement at a feed position thereon between the top and bottom thereof for separation within the distillation tower arrangement;
compressing the second proportion to an increased pressure higher than the feed pressure, the increased pressure being selected to provide a desired operating pressure in the distillation tower arrangement and being different from the residue gas pressure;
extracting heat from the compressed second proportion to effect condensation thereof;
sub-cooling the compressed condensed second proportion;
expanding the compressed condensed second proportion and supplying the second proportion after expansion to the distillation tower arrangement at a position thereon adjacent the top of the distillation tower arrangement so as to cause cooling of the materials in the distillation tower arrangement.

6 more elements

A method of separating heavier components from natural gas comprising:

providing a distillation tower arrangement for separating the heavier components discharged at the bottom of the tower arrangement from lighter gas discharged at the top of the tower arrangement;
providing a feed gas containing the components for supply to the distillation tower arrangement;
the tower arrangement including at least two separate towers at different pressures thus defining a higher pressure tower and a lower pressure tower each arranged to separate a lighter product at the top and a heavier product at the bottom of the respective tower;
taking the heavier product from the bottom of the higher pressure tower which is then expanded and fed to the lower pressure tower;
separating the feed gas into a first proportion and a second proportion, where neither proportion is zero;
feeding the first proportion to the distillation tower arrangement at a feed position thereon between the top and bottom thereof for separation within the distillation tower arrangement;
adding at least a portion of the lighter gas from the top of the lower pressure tower to the second proportion for processing therewith and supply to the top of the higher pressure tower;
compressing said second proportion and said at least a portion of the lighter gas from the top of the lower pressure tower to a pressure higher than the feed pressure;
extracting heat from said second proportion and said at least a portion of the lighter gas from the top of the lower pressure tower to effect condensation thereof;
sub-cooling said second proportion and said at least a portion of the lighter gas from the top of the lower pressure tower;
expanding said second proportion and said at least a portion of the lighter gas from the top of the lower pressure tower;
and supplying said second proportion and said at least a portion of the lighter gas from the top of the lower pressure tower after expansion to the higher pressure tower together at a common position thereon adjacent the top so as to cause cooling of the materials in the distillation tower arrangement.

9 more elements

Dependencies are inferred from the claim text.

Thermodynamic separation of heavier components from natural gas

Life of this patent

Thermodynamic separation of heavier components from natural gas

Life of this patent

Abstract

Claims20