A process for producing biomethane by scrubbing a biogas feed stream, including introducing a feed gas stream into a pretreatment unit thereby partially separating a CO.sub.2 stream and an oxygen stream and producing a CO.sub.2-depleted gas stream which is then compressed to a pressure P1 above 25 bar abs; introducing the CO.sub.2-depleted gas stream to cryogenic separation in a distillation column to separate a nitrogen stream, the distillation column having n plates, n being an integer between 8 and 100; recovering a pressurized CH.sub.4-enriched stream by pumping the CO.sub.2-depleted gas stream) at a pressure P2 above 25 bar, wherein, when the molar concentration of nitrogen of the CO.sub.2-depleted gas stream is less than a predetermined threshold, nitrogen is injected prior to introduction into the distillation column, in order that the stream introduced into said column has a molar concentration of nitrogen at least equal to said predetermined threshold.

A helium-containing stream is recovered from a natural gas feed using a membrane followed by multiple distillation steps. Refrigeration is provided by expanding a bottoms liquid with a higher nitrogen content than the feed, achieving a lower temperature in the process. The helium-enriched vapor is then purified and the helium-containing waste stream is recycled to maximize recovery and reduce the number of compressors needed. The helium-depleted natural gas stream can be returned at pressure for utilization or transportation.

A process and facility for producing gaseous methane by purifying biogas from landfill, can include a VOC purification unit, at least one membrane, a booster, a CO.sub.2 purification unit, a cryodistillation unit comprising a heat exchanger, a distillation column, and a subcooler, a deoxo, and a dryer.

A thin film composite gas separation membrane comprising a polyether block amide copolymer coating layer and a nanoporous asymmetric support membrane with nanopores on the skin layer surface of the support membrane and gelatin polymers inside the nanopores on the skin layer surface of the support membrane. A method for making the thin film composite gas separation membrane is provided as well as the use of the membrane for a variety of separations such as separations of hydrogen sulfide and carbon dioxide from natural gas, carbon dioxide removal from flue gas, fuel gas conditioning, hydrogen/methane, polar molecules, and ammonia mixtures with methane, nitrogen or hydrogen and other light gases separations, but also for natural gas liquids recovery and hydrogen sulfide and carbon dioxide removal from natural gas in a single step.

The present invention relates to a low-temperature membrane separation device and method for capturing carbon dioxide at a high concentration, in which a gas mixture is passed through a membrane unit to thus separate carbon dioxide. The membrane unit includes a membrane for capturing carbon dioxide and is connected to a feed gas line, a retentate gas line and a permeate gas line. The method includes a first separation step of passing the gas mixture through a first membrane unit and a second separation step of passing the permeation gas, which is discharged to the permeate gas line connected to the first membrane unit, through a second membrane unit. The second separation step is performed at a temperature that is lower than a temperature at which the first separation step is performed.

A process and facility for producing gaseous methane by purifying biogas from landfill can include a VOC purification unit, at least one membrane, a CO.sub.2 purification unit, a cryodistillation unit comprising a heat exchanger and a distillation column, a deoxo, and a dryer.

The invention relates to a method and a device for separating carbon dioxide from a respiratory gas mixture. The separation is carried out by means of a membrane which acts as a molecule filter.

Recovering helium from a gaseous stream includes contacting an acid gas removal membrane with a gaseous stream to yield a permeate stream and a residual stream, removing a majority of the acid gas from the residual stream to yield a first acid gas stream and a helium depleted clean gas stream, removing a majority of the acid gas from the permeate stream to yield a second acid gas stream and a helium rich stream, and removing helium from the helium rich stream to yield a helium product stream and a helium depleted stream. A helium removal system for removing helium from a gaseous stream including hydrocarbon gas, acid gas, and helium includes a first processing zone including a first acid gas removal unit, a second processing zone including a second acid gas removal unit, a third processing zone, and a helium purification unit.

The invention relates to a reefer container (1) having a controlled atmosphere system (3) comprising:a first selective unit (4) comprising an absorber or a membrane (9) being selective for carbon dioxide over oxygen and nitrogen;a second selective unit (11) comprising an absorber or a membrane (14) being selective for oxygen over nitrogen; anda vacuum pump (6) for extracting and removing separated gasses from a permeate side (8, 13) of the first and second selective units (4, 11) to outside the container(1), where the system (3) is further comprising a pump (15) for providing an overpressure in the container(1). The pump (15) can be connected to the container (1) through a feed side (12) of the second selective unit (11). The invention further relates to a method of controlling reefer container (1) having a controlled atmosphere system (3).

A facility and method for membrane permeation treatment of a feed gas flow containing at least methane and carbon dioxide that includes a compressor, a pressure measurement device, at least one valve, and first, second, third, and fourth membrane separation units for separation of CO.sub.2 from CH.sub.4 to permeates enriched in CO.sub.2 and retentates enriched in CH.sub.4, respectively. The at least one valve adjusts the number of membranes combined and connected to the flow of gas entering into at least one of the membrane separation units as a function of the pressure recorded by the pressure measurement device.