Abstract: The invention relates to a device for separating a gas mixture into a product gas and an offgas by gas permeation, having a membrane unit (I) and a compressor (3) that is connected upstream of the membrane unit (I) and is preferably adjustable in terms of rotational speed, which membrane unit (I) has a gas inlet (I a), an outlet (I b) for retentate or product gas, and an outlet (I c) for permeate or offgas, wherein the membrane unit (I) has at least one other permeate outlet (1c?) that is downstream of the gas inlet (1a), and the permeate outlet (1c?) of the membrane unit (I) is connected by lines on the suction side to the compressor (3) or to the gas supply leading into the compressor, and wherein a pressure-regulating device (2) is provided at or downstream of the retentate outlet (Ib), and use is made of a gas mixture, consisting primarily of CH4/CO2 and having a methane concentration of not greater than 30% by volume; and to the use of such a device and to a corresponding method.

Abstract: A device for separating a gas mixture into product gas and offgas by way of gas permeation includes four membrane units and a compressor connected upstream of the first membrane unit. The membrane units have a gas inlet, a retentate outlet and a permeate outlet. Lines connect the membrane units to each other and to the compressor. Product gas is obtained via the permeate outlet of the second membrane unit and offgas via the retentate outlet of the first membrane unit. Additional product gas is obtained via the retentate outlet of an upstream membrane unit and additional offgas is obtained via the permeate outlet of a further upstream membrane unit. A method includes use of the device to separate a gas mixture into product gas and offgas.

Abstract: The invention relates to a device for separating a gas mixture into product gas and offgas by way of gas permeating on, comprising at least two membrane units (1) and (2) and a condenser (3) connected upstream of the first membrane unit (1), which membrane units (1) and (2) have a gas inlet (1a, 2a), a retentate outlet (1b, 2b) and a permeate outlet (1c, 2c), wherein the retentate outlet (1b) of the first membrane unit (1) is connected to the gas inlet (2a) of the second membrane unit (2), the permeate outlet (2c) of the second membrane unit (2) is connected on the intake side to the condenser (3) or the gas supply leading into the condenser, and the condenser (3) is connected to the gas inlet (1a) of the first membrane unit (1), the connection in each case being by way of lines, product gas is obtained via the permeate outlet (2a) and offgas via the retentate outlet (1c), wherein the permeate outlet (4c) of an upstream membrane unit (1) is connected to the gas supply of the condenser (3) by way of lines, whe