Patent ID: 11866667
Assignee: LIQUIDE ADVANCED TECHNOLOGIES U.S. LLC
Field: Chemical engineering (Chemistry)
Classification: CPC C  B  F  Y | IPC B  C  F

Claim 4:
5. A process for dewpointing natural gas that provides for recovery of NGL, comprising the steps of:
feeding a flow of associated gas, that does not meet a predetermined specification(s) for hydrocarbon dewpoint and/or a gross heating value, to a first gas separation membrane-based separation stage comprising one or more gas separation membranes selective for C2+ hydrocarbons over methane to produce a flow of a first permeate enriched in C2+ hydrocarbons and a flow of a first retentate enriched in methane;
chilling the first permeate to provide a flow of chilled first permeate;
separating the flow of chilled first permeate to produce a flow of a first gaseous phase deficient in C3+ hydrocarbons and a flow of a first liquid phase enriched in C3+ hydrocarbons;
recovering the flow of the first liquid phase as NGL;
feeding the flow of a first retentate, that does not meet a predetermined specification for gross heating value, to a second gas separation membrane-based separation comprising one or more gas separation membranes selective for C2+ hydrocarbons over methane to produce a flow of a second permeate enriched in C2+ hydrocarbons and a flow of a second retentate enriched in methane that meets the predetermined specification;
recovering the flow of a second retentate, the recovered second retentate meeting a predetermined specification(s);
compressing the flow of second permeate; and
feeding the flow of compressed second permeate along with the flow of associated gas to the first gas separation membrane-based separation stage,
wherein the flow of natural gas has not been compressed prior to being fed to the first gas separation membrane-based separation stage, the flow of natural gas having a pressure of 15-100 bar, and wherein the process further comprises the step of feeding the flow of first gaseous phase to a third gas separation membrane-based separation unit comprising one or more gas separation membranes selective for CO2 over methane to produce a flow of a third permeate enriched in CO2 and a flow of a third retentate enriched in methane, wherein the flow of second permeate and the flow of third retentate are combined and compressed prior to being fed to the first gas separation membrane-based separation stage.