| 摘要 |
The invention relates to a method for obtaining a helium-containing product fraction (8) from a feed fraction (1, 3) which in addition to helium has at least one component which permeates more poorly than helium through a membrane, in particular nitrogen and/or methane, wherein a) the feed fraction (1, 3) is subjected to a first membrane separation process (M1), b) the first helium-enriched permeate stream (5) obtained thereby is mixed (6) with a helium-containing recycle stream (13), compressed (V), and subjected to a second membrane separation process (M2), c) the second helium-enriched permeate stream (7) obtained thereby is subjected to a pressure swing adsorption process (A) or a fourth membrane separation process, d) wherein the helium-containing stream obtained in the pressure swing adsorption process (A) or in the fourth membrane separation process constitutes the product fraction (8), e) the second helium-depleted retentate stream (10) produced in the second membrane separation process (M2) is subjected to a third membrane separation process (M3), and f) the third helium-enriched permeate stream (12) obtained thereby is mixed with the flushing gas stream (9) produced in the pressure swing adsorption process (A) or with the helium-depleted retentate stream produced in the fourth membrane separation process to give the recycle stream (13). |
