According to one embodiment, a gas recovering apparatus includes a casing and a tube. The casing is provided with an inlet through which a gas flows in, a first outlet for discharging a first gas containing a gas to be recovered of the gas, and a second outlet for discharging a second gas other than the first gas of the gas. The casing is evacuated via the first outlet. The tube is provided in the casing from the inlet to the second outlet, and has a high permeability to the first gas and a low permeability to the second gas.

A process comprising: subjecting a process gas containing NOx to a stage for absorption of NOx in a suitable absorption means, obtaining nitric acid and a tail gas containing nitrogen, argon and residual NOx; subjecting said tail gas to a treatment which comprises at least one NOx removal stage, obtaining a conditioned tail gas; subjecting at least a portion of said conditioned tail gas to a separation treatment, obtaining a product stream containing argon and a product stream containing nitrogen.

In a helium purification process, a stream containing at least 10% of helium, at least 10% of nitrogen in addition to hydrogen and methane is separated to form a helium-enriched stream containing hydrogen, a first stream enriched in nitrogen and in methane and a second stream enriched in nitrogen and in methane, the helium-enriched stream is treated to produce a helium-rich product and a residual gas containing water, the residual gas is treated by adsorption (TSA) to remove the water and the regeneration gas from the adsorption is sent to a combustion unit (O).

The invention provides a method and system for separating xenon-krypton mixed gas by hydrate formation process. The system is mainly composed of a gas hydrate generating unit, a heat exchanging unit and a gas-water separating unit: pre-cooled xenon-krypton mixed gas is injected from a bottom of a reaction tower, xenon gas in the mixed gas and water attached to a porous tray generate a xenon gas hydrate; and water is injected from a top of the tower to wet the porous tray, a generated hydrate particle is washed and collected to the bottom of the tower simultaneously to form a hydrate slurry, after passing through the heat exchanging unit, the xenon gas hydrate in the slurry is decomposed to form a gas phase flow and a water phase flow, and then enters the gas-water separating unit, and the xenon gas is separated from decomposed water.

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.

In a helium purification process, a stream containing at least 10% of helium, at least 10% of nitrogen in addition to hydrogen and methane is separated to form a helium-enriched stream containing hydrogen, a first stream enriched in nitrogen and in methane and a second stream enriched in nitrogen and in methane, the helium-enriched stream is treated to produce a helium-rich product and a residual gas containing water, the residual gas is treated by adsorption (TSA) to remove the water and the regeneration gas from the adsorption is sent to a combustion unit (O).

An apparatus for collecting helium gas includes: a first receptacle having a first flexible membrane for receiving a gas containing helium, the first receptacle being selectively couplable to an inlet of the apparatus; a second receptacle having a second flexible membrane for receiving the gas containing helium, the second receptacle being selectively couplable to the inlet of the apparatus; a pump having an inlet selectively couplable to an outlet of the first receptacle and selectively couplable to an outlet of the second receptacle; a purifier having an inlet couplable to an outlet of the pump; and an outlet of the apparatus couplable to an outlet of the purifier. A method of collecting and reusing helium gas is also described. Other valuable and/or rare gases may be recovered and reused.

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.

A process comprising: subjecting a process gas containing NOx to a stage for absorption of NOx in a suitable absorption means, obtaining nitric acid and a tail gas containing nitrogen, argon and residual NOx; subjecting said tail gas to a treatment which comprises at least one NOx removal stage, obtaining a conditioned tail gas; subjecting at least a portion of said conditioned tail gas to a separation treatment, obtaining a product stream containing argon and a product stream containing nitrogen.

A method of removing buffer gas from a mixture comprising the buffer gas and hyperpolarized noble gas is described. The method includes reacting the buffer gas to produce a reaction product different to the buffer gas. The buffer gas may be reactively removed by one or more of oxidation, reduction, polymerization and binding reactions with solid surfaces. The buffer gas may be molecular hydrogen and/or molecular nitrogen. Apparatus for carrying out the method are also disclosed.