To recover moisture contained in exhaust gas discharged from a co-generation device.

Humid exhaust gas discharged from a power generation device 11 as the co-generation device is introduced in the direction of an arrow A, and dry exhaust gas discharged from a moisture recovering means 14 after moisture only is recovered is discharged outdoors in the direction of an arrow B. Next, moisture absorbed from humid exhaust gas accumulated in the moisture recovering means 14 that is rotating in the direction of an arrow C is moved downward in the illustration, while dry air from the outdoor side is introduced in the direction of an arrow D to be taken into the moisture recovering means 14. Moisture in the moisture recovering means 14 is thus absorbed into dry air to be changed into humid air to be introduced in the direction of an arrow E, and humid air is atomized from a nozzle 20. A control circuit comprises a control device 24 to control rotation speed of the moisture recovering means 14 based on difference between actual moisture detected by a temperature sensor 23 and target moisture predetermined, and a motor 25 rotated based on an instruction from the control device 24.