Hydrogen gas recovery system and hydrogen gas separation and recovery method

The amount of supplemental hydrogen, which is used for separating the reactant exhaust of a polycrystalline silicon production apparatus, is reduced as much as possible. Reactant exhaust, in which a chlorosilane and hydrogen chloride have been removed by a hydrogen chloride absorption apparatus (30), is introduced into an adsorption apparatus (50), and purified hydrogen is recovered (S105). The purified hydrogen is obtained by packing an activated carbon into the adsorption apparatus (50) and, while a gas consisting mainly of hydrogen is passed through said layer of packed activated carbon, removing the unseparated chlorosilane and hydrogen chloride, as well as nitrogen, carbon monoxide, methane, and monosilane, which are comprised within the gas, from said gas by means of adsorption to the activated carbon. Though the nitrogen, carbon monoxide, methane, and monosilane are compressed gas in an adsorbed state, the hydrogen chloride and chlorosilane are liquid in an adsorbed state and thus require application of the heat of vaporization during desorption. Using this feature, the separation of hydrogen chloride and chlorosilane from other impurities is possible merely by separating the pathways of the desorption gas.