A system for separating olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor includes a heat exchanger that receives and partially condenses the effluent fluid stream so that a mixed phase effluent stream is formed. A primary separation device receives and separates the mixed phase effluent stream into a primary vapor stream and a primary liquid product stream. A heat exchanger receives and partially condenses the primary vapor stream so that a mixed phase primary stream is formed. A secondary separation device receives and separates the mixed phase primary stream into a secondary vapor stream and a secondary liquid product stream. A heat exchanger receives and warms the secondary vapor stream to provide refrigeration for partially condensing the effluent fluid stream and a heat exchanger receives and warms the secondary vapor stream to provide refrigeration for partially condensing the primary vapor stream. A mixed refrigerant compression system provides refrigerant to a heat exchanger to provide refrigeration.

In a process for separating carbon dioxide from a waste gas (3) of a fluid bed catalytic cracking installation (1) containing carbon dioxide, nitrogen and possibly carbon monoxide, the waste gas (3) is separated by adsorption to form a gas enriched in carbon dioxide and depleted in nitrogen (29) and a gas rich in nitrogen and depleted in carbon dioxide (31), and at least a portion of the gas enriched in carbon dioxide and depleted in nitrogen is separated in a separation device (30) by way of separation at a temperature of less than 0° C. by partial condensation and/or by distillation to form a fluid rich in carbon dioxide (35) and a fluid depleted in carbon dioxide (37).

A process for purifying a gaseous feed stream of natural gas including methane, CO.sub.2 and heavy hydrocarbons including step a): cooling the gaseous feed stream in a heat exchanger; step b): introducing the cooled stream into a phase-separating chamber to produce a liquid stream depleted in methane and enriched in heavy hydrocarbons and a gaseous stream; step c): separating the gaseous stream obtained from step b) in a first membrane producing at least one CO.sub.2-enriched permeate stream and a residual stream enriched in methane; step d): introducing the residual stream obtained from step c) into a phase-separator to produce a liquid stream and a gaseous stream; step e): heating the gaseous stream obtained from step d) by introducing it into the heat exchanger used in step a) counter-currentwise with the feed stream thereby producing a gaseous stream depleted in CO.sub.2 and enriched in methane.

Process for producing biomethane from a biogas stream including methane, carbon dioxide and at least one impurity chosen from ammonia, volatile organic compounds, water, sulfur-based impurities (H.sub.2S) and siloxanes. A biogas stream is dried, the at least one impurity is at least partially removed by solidification and removal of the impurity. The methane and the carbon dioxide contained in the biogas obtained from the second step are separated so as to produce a biomethane stream and a CO.sub.2 stream.

Device and method for the cryogenic purification of a stream of gas, comprising a purification circuit comprising a first inlet and a first set of filters arranged in series, the first set of filters comprising a terminal heat exchanger in a heat-exchange relationship with a cold source, the purification circuit comprising, downstream of the terminal exchanger, a first outlet, the device comprising at least one drive member intended to set the stream of gas in motion in the circuit, the purification circuit further comprising, between the terminal exchanger and the first outlet, a second set of filter(s), and the at least one drive member being configured to set two successive volumes of gas for purification in motion in opposite directions of circulation in the circuit. The invention also relates to a machine including such a device.

In a process for the separation of a mixture containing hydrogen and carbon monoxide to produce gaseous hydrogen, the mixture is cooled down to a temperature below −180° C. and then separated at a temperature below −100° C. to produce a gas enriched in hydrogen and a fluid enriched in carbon monoxide, at least a part of the gas enriched in hydrogen is sent to a pressure swing adsorption separation apparatus operating at a temperature above 0° C. to produce a gas rich in hydrogen at a pressure of at least 20 bars, and at least a part of the gas rich in hydrogen is cooled in the heat exchanger down to a temperature below −100° C., reduced in pressure in a turbine down to a pressure of at least 8 bars and reheated in the heat exchanger to constitute a product rich in hydrogen at a pressure of at least 8 bars.

A thermally integrated separation method, including exchanging heat indirectly between an inlet stream and a liquid carbon dioxide/NGL containing stream in a heat exchanger, thereby producing a cold inlet stream and a vaporized carbon dioxide/NGL containing stream, introducing the cold inlet stream into a cryogenic separation unit, thereby producing the liquid carbon dioxide/NGL containing stream and a methane-rich stream, introducing the methane-rich stream into a membrane separation unit, thereby producing a methane rich product stream, and a permeate stream, and introducing the vaporized carbon dioxide/NGL containing stream into a carbon dioxide/NGL separation unit, thereby producing a carbon dioxide rich product stream and a NGL rich product stream. Wherein, at least a portion of the liquid carbon dioxide/NGL containing stream bypasses the heat exchanger and is introduced into the carbon dioxide/NGL separation unit in liquid phase.

Processes and apparatuses for recovering a high purity carbon dioxide stream. A first separation zone that may include a cryogenic fractionation column provides the high-purity CO.sub.2 stream. A vapor stream from the cryogenic fractionation column is passed to a second separation zone to separate the CO.sub.2 from the other components. The second separation zone may include a pressure swing adsorption unit or a solvent separation unit. The second separation zone provides a hydrogen enriched gas stream that may be used in a gas turbine. The second stream from the second separation zone includes carbon dioxide and, after a pressure increase in a compressor, may be recycled to the first separation zone.

The invention relates to a process (100) for producing liquefied natural gas using a feedstock mixture that contains at least methane, one or more components boiling at a temperature lower than methane and one or more hydrocarbons boiling at a temperature higher than methane, wherein the hydrocarbon(s) boiling at a temperature higher than methane comprise one or more hydrocarbons freezing at a higher temperature, with a freezing point higher than −50° C. According to the invention the feedstock mixture is fed into a pressure swing adsorption process (10), in which a first fraction containing methane and a second fraction containing methane are formed, the first fraction containing methane contains, in addition to the methane, at least the predominant portion of the components of the feedstock mixture that boil more readily than methane and is low in or free from the hydrocarbons boiling less readily than methane, and the second fraction containing methane contains, in addition to the methane, at least the predominant portion of the hydrocarbons from the feedstock that boil less readily than methane and is low in or free from the components that boil more readily than methane, and the first fraction containing methane, or a portion thereof, is supplied for liquefaction (20). The invention also relates to a corresponding plant.

A pressurized CO.sub.2 rich gas is cooled down to condense at least part of the stream in a heat exchanger. A bulk of the CO.sub.2 is separated by partial condensation and distillation in order to obtain at least one non-condensable gas from a separation vessel. The non-condensable gas is optionally heated up to a temperature lower than −20° C. (membranes performances is greatly enhanced by low temperature operation). The non-condensable gas is introduced into a membrane permeation unit, producing a residue stream and a permeate stream (the permeate stream is enriched in CO.sub.2). The permeate stream is recycled to the process, optionally after compression. The method is auto-refrigerated, i. e. no external refrigerant is used to provide cooling below 0° C.