Method for producing liquid and gaseous nitrogen streams, a helium-rich gaseous stream, and a denitrogened hydrocarbon stream, and associated plant

摘要

The method of the invention includes cooling an inlet stream (72) within an upstream heat exchanger (28). The method includes feeding the cooled inlet stream (76) into a fractioning column (50) and collecting the denitrogenated hydrocarbon stream at the bottom of the column (50). The method includes feeding a nitrogen-rich stream (106) from the head of the column (50) into a disengager (60) and collecting the gaseous head stream from the disengager (60) in order to form the helium-rich stream (20). The liquid stream (110) from the base of the first disengager (60) is separated into a liquid nitrogen stream (18) and into a first reflux stream (114) that is fed as a reflux into the head of the fractioning column (50).