PURPOSE: To separate working fluid from absorbent liquid of rich carbonic acid gas efficiently after cleaning by providing a carbonic acid gas absorbing liquid regenerating device for regenerating the rich liquid to lean absorbent liquid and a centrifugal separator for separating the working fluid and rich absorbent liquid from each other after cleaning.

CONSTITUTION: Lubricant in a diesel engine 1 can heat, by a heat exchanger 11 rich absorbent liquid sent to a carbonic acid gas absorbing liquid regenerating device 17 through a lubricant flow passage shown with an arrow mark C. The rich absorbent liquid separated by a centrifugal separator 22 is given heat by heat exchanging with lean absorbent liquid in a heat exchanger 3, further, after being heated by the heat exchanger 11, introduced from the absorbent liquid entrance 31 of the carbonic acid gas absorbing liquid regenerating device 17, and after discharging carbonic acid gas, discharged from an absorbent liquid exit 32 as lean absorbent liquid.