Disclosed is a method for purifying a main gas, in particular helium, from a source gas stream comprising the main gas, a main impurity, in particular nitrogen, and optionally another, secondary impurity, in particular oxygen, the method comprising a step of partial condensation of the gas stream in order to extract therefrom impurities in liquid form, in particular the main impurity, and to produce a gas stream enriched with main gas, characterized in that the method comprises, before the partial condensation step, a step of injecting into the gas stream a compound in which the main impurity of the gas to be treated is soluble and having a saturation vapor pressure lower than the saturation vapor pressure of the main impurity.

The present invention provides systems and methods for simultaneously producing a high-purity helium gas product, a methanol-water liquid mixture, and a methane-rich fuel product from a hydrogen-rich feedstock gas containing helium by treating the hydrogen-rich feedstock gas containing helium and carbon dioxide in a reverse water gas shift unit (1500) to produce carbon monoxide, which is then treated in a methanol production unit (300) and a methanol absorption unit (400) to produce a methanol-aqueous solution and a methanol-free gas. The methanol-free gas is then treated in a methane production unit (500) to produce methane, which is then treated in a carbon dioxide recovery membrane unit (1100) and a cryogenic nitrogen rejection unit (600) to produce the methanol-water liquid mixture, the methane-rich fuel product, and a helium-rich gas. The helium-rich gas is then treated to produce the high-purity helium gas product.

System for purifying argon by cryogenic distillation, comprising a single column surmounted by a top-end condenser, a fluid inlet in the lower part of the column, a fluid outlet in the upper part of the column, and N distillation sections where N4, of which at least the two uppermost sections of the column are equipped respectively with a first liquid distributor and with a second liquid distributor, the second distributor being capable of performing a function of mixing together liquids that fall onto the distributor, each of the first and second distributors being positioned above the respective section and of which the two lowermost sections of the column are respectively equipped with a (N1)th and an Nth liquid distributor capable of performing a function of mixing together liquids that fall onto the distributor, and which is arranged above the respective section, the first, second, (N1)th and Nth distributors each being dimensioned to contain a maximum height of liquid head, that (those) of the first and second distributors being greater than that (those) of the (N1)th and Nth distributors.