NOVELTY - A gas-separation apparatus (1) consists of adsorption towers (2A,2B) which adsorbs the specific component in the mixed gas (BB) and includes a heat exchanger tube, and a heat-medium circulation path (3) which circulates a heat medium. By using the heat medium, the heat medium circulation path transfers the adsorption heat of the adsorption tower which is adsorbing and the temperature of which becomes higher than the external temperature, to the adsorption tower which is being regenerated.    USE - Gas-separation apparatus is used for separating specific component e.g. carbon dioxide and water, from mixed gas e.g. biogas and combustion exhaust gas, comprising several components (all claimed). Biogas is emitted from fermenter used in processing of sewage works, livestock excrement, and organic refuse.    ADVANTAGE - The gas-separation apparatus has a configuration which reduces the number of devices compared to the past and efficiently separates specific components from mixed gas. Heat energy can be used effectively.    DETAILED DESCRIPTION - A gas-separation apparatus consists of adsorption towers which adsorbs the specific component in the mixed gas and includes a heat exchanger tube, and a heat-medium circulation path which circulates a heat medium among the adsorption towers between the heat exchanger tube of the adsorption tower during adsorption and the heat exchanger tube of the adsorption tower during regeneration. By using the heat medium, the heat medium circulation path transfers the adsorption heat of the adsorption tower which is adsorbing and the temperature of which becomes higher than the external temperature, to the adsorption tower which is being regenerated. The adsorption tower which is being regenerated is regenerated at a pressure lower than the adsorption tower which is adsorbing and at a temperature below the external temperature and also exchanges heat with the air outside the adsorption tower which is being regenerated.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the biogas separation-and-recovery system. (Drawing includes non-English language text)    Gas-separation apparatus (1)    Adsorption towers (2A,2B)    Heat-medium circulation path (3)    Pressure equalization buffer tank (4)    Biogas as mixed gas (BB)