It is an extractant-containing gas that is extracted and dried, and the extractant is adsorbed by activated carbon. After the activated carbon is saturated with adsorption for a period of time, the activated carbon is regenerated using steam. After the steam purges the activated carbon, the steam containing the extractant is condensed into a liquid through a condenser, separated into the extractant storage tank by specific gravity, and the water is pumped back to the pool. Dry hot activated carbon with hot air to make it better for the next step of adsorption.