PROBLEM TO BE SOLVED: To provide a method for generating a gas, which can increase output pressure of a product gas while increasing the concentration and recovery rate of a target gas to be concentrated for the product gas.SOLUTION: The method for generating a gas uses the pressure swing adsorption technique that performs following steps by switching successively adsorption towers AT1, AT2 and AT3: an adsorption step of generating the product gas G2 by supplying a raw material gas G1 to the terminal of the primary side of an adsorption tower AT&alpha a recovery step of recovering the adsorption power of an adsorbent by lowering the internal pressure of an adsorption tower AT&beta after completing the adsorption process a pressure increasing step of increasing the internal pressure by supplying the raw material gas G1 to an adsorption tower AT&gamma in which the next adsorption process is performed. In the method, among the raw material gas G1 (pressure-increased gas G5) supplied to the adsorption tower AT&gamma, the pressure-increased gas G5, which has reached to the terminal of the secondary side of the AT&gamma and has the concentration higher than that of the initial target gas to be concentrated but not yet enough for the product gas G2, is taken out from the terminal of the secondary side of the adsorption tower AT&gamma and is blown into the adsorption tower AT&beta as a purged gas G6.COPYRIGHT: (C)2012,JPO&INPIT【課題】製品ガスの取出圧力を高くでき、製品ガスにおける濃縮対象ガスの濃度と回収率を高めることが可能なガス生成方法を提供する。【解決手段】吸着塔ATαの一次側の端部に原料ガスG1を供給して製品ガスG2を生成する吸着工程と、吸着工程を終えた吸着塔ATβの内部圧力を低下させて吸着剤の吸着能を再生する再生工程と、次に吸着工程が行われる吸着塔ATγに原料ガスG1を供給することによりその内部圧力を高める昇圧工程とを、吸着塔AT1,AT2,AT3で順次切り替えながら行う圧力変動吸着式のガス生成方法において、吸着塔ATγに供給された原料ガスG1(昇圧ガスG5)のうち、吸着塔ATγの二次側の端部に達して当初よりも濃縮対象ガスの濃度が高まったものの製品ガスG2には達しない昇圧ガスG5を吸着塔ATγの二次側の端部から抜き取り、吸着塔ATβへパージガスG6として吹き込むようにした。【選択図】図4
