Method for the simultaneous recovery of a pure helium and pure nitrogen fraction

A process for simultaneous recovery of a pure helium and a pure nitrogen fraction from a feed stream containing at least methane, nitrogen and helium, wherein:

• the feed stream is partially condensed and separated into a helium-rich gas fraction and a nitrogen- and methane-rich liquid fraction;
• the helium-rich gas fraction is conveyed to a purification stage in which a pure helium fraction is recovered by adsorption, permeation and/or rectification;
• and
• at least one partial stream of the nitrogen- and methane-rich liquid fraction is taken to a rectification process for recovery of a pure nitrogen fraction.

A process for recovery of a pure helium fraction and a pure nitrogen fraction from a feed stream containing at least methane, nitrogen and helium, comprising the steps of:

• partially condensing the feed stream in a heat exchanger;
• separating the partially condensed feed stream into a helium-rich gas fraction and a nitrogen- and methane-rich liquid fraction;
• recovering a pure helium fraction from the helium-rich gas fraction in a purification stage;
• and
• recovering a pure nitrogen fraction from a partial stream of the nitrogen- and methane-rich liquid fraction in a rectification column.