Method for Separating Trace Components from a Nitrogen-Rich Stream

A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction present at a pressure of at least 10 bar, wherein from a starting stream containing at least methane, nitrogen, helium and hydrogen, a pure helium and nitrogen fraction is extracted by:

• partially condensing the starting stream and separating it into a helium-rich gas fraction and into a first nitrogen-rich liquid fraction,
• conducting the helium-rich gas fraction to a post-cleaning stage in which by adsorption, permeation and/or rectification a pure helium fraction is obtained where a helium-depleted fraction accumulating in the post-cleaning stage is returned to the starting stream,
• separating the first nitrogen-rich liquid fraction into a helium-depleted gas fraction which is similarly returned to the starting stream, and into a second nitrogen-rich liquid fraction, and
• taking at least one partial stream of the second nitrogen-rich liquid fraction to a rectificatory pure nitrogen fraction extraction,
• wherein a nitrogen-rich liquid fraction drawn off from the rectificatory pure nitrogen fraction extraction is at least partially expanded and subjected to phase separation, wherein the expansion takes place at a pressure which allows a separation of hydrogen, helium and/or neon except for residues of less than 20 ppmV.

A method for separating hydrogen, helium and/or neon from a nitrogen-rich liquid fraction, comprising the steps of:

• expanding the nitrogen-rich liquid fraction to a pressure;
• and
• phase separation of the expanded nitrogen-rich liquid fraction in a precipitator;
• wherein the pressure is such that the phase separation separates the hydrogen, helium and/or neon such that a residual content of hydrogen, helium and/or neon is less than 20 ppmV in the nitrogen-rich liquid fraction.