Abstract: A method for recovering helium from a feed gas mixture comprising helium, carbon dioxide and at least one of methane and nitrogen, and wherein at least a part of the feed gas mixture is subjected to a separation sequence including a membrane-based separation and an adsorption-based separation forming a helium product, wherein the the membrane based separation is performed using a first membrane separation step and a second membrane separation step, the membrane based separation and the separation sequence includes no further membrane separation steps, the adsorption based separation is performed using a pressure swing adsorption step, at least a part of the feed gas mixture is subjected to the first membrane separation step forming a first retentate and a first permeate. A corresponding arrangement is also provided.

Abstract: A membrane separation unit wherein the membrane separation unit has a pressure vessel and a membrane provided inside the pressure vessel in a membrane arrangement, and wherein the pressure vessel has an inlet nozzle for a feed gas mixture, an outlet nozzle for a permeate and an outlet nozzle for a retentate. The membrane separation unit has in this case measurement means that are arranged at least partially inside the pressure vessel and/or inside the inlet nozzle for the feed gas mixture and/or inside the outlet nozzle for the permeate and/or inside the outlet nozzle for the retentate and are set up to record one or more parameters relevant to operation.