Membrane separation method for enriching at least one gas component in a gas stream

The invention relates to a membrane separation process for enriching at least one gas component in a gas stream, especially for oxygen enrichment of air (7), wherein the gas stream for the enrichment of the gas component at least one at least one membrane having the membrane separation unit (10) of a membrane separating device (2) is fed, and wherein at of the membrane takes place, the separation of the gas stream in an on a retentate side (12) of the membrane abgefuhrtes retentate (8) and in a on a permeate side (11) of the membrane abgefuhrtes permeate (9). To enable the gas separation and the enrichment of a gas component in a gas stream at low energy consumption and low capital and operating costs, it is provided that the gas flow before entry into the membrane separating device (2) is compressed to an input pressure above ambient pressure and that the pressure level on the permeate side (11) is lowered relative to the input pressure of the gas stream.