Gas purification method

A gas purification method for obtaining a purified gas by passing a feed gas containing water vapor and carbon dioxide as impurities through a plurality of adsorption columns which are packed with an adsorbent adsorbing the impurities and can be used switchably, and thus removing the impurities, the method comprising the steps of:

• (a) an adsorption step of adsorbing and removing the water vapor first and then the carbon dioxide by introducing compressed said feed gas into the adsorption columns, said feed gas in the adsorption step being introduce into the adsorption columns at a temperature within a range of 30° C. through 45° C.;
• (b) a depressurization step of lowering internal pressure of the adsorption columns down to atmospheric pressure after the adsorption step;
• (c) a heating step of heating and regenerating the adsorbent by introducing a purge gas not containing the impurities into the adsorption columns after the depressurization step, said purge gas supplying heat to the adsorption columns in the heating step of 0.5 or more relative to heat supplied to the adsorption columns by the feed gas in the adsorption step;
• and
• (d) without cooling after the heating step, a repressurization step of elevating pressure by introducing a gas not containing the impurities into the adsorption column;
• wherein the respective periods of time of the respective steps (a), (b+c) and (d) are each set to be within the range of 15 to 25 min.