PURPOSE: To generate stably and efficiently steam and to condense and recover this by heating a liq. film-like substance by energizing electricity in evaporation and recovery of the substance.
CONSTITUTION: A liquified substance 13 is stored in an upper container and this is dropped in a liq. film on the surface of a cylindrical insulating cylinder 15 provided below it. The liq. film is recovered in the lower container 14 and an electric source is connected to the upper and lower container and only when the liq. film bridges the upper and lower containers, surface heating by energizing electricity is performed and steam 19 is generated. Almost all fed energy is consumed as energy for generating steam 19 and not only evaporation efficiency is improved but also energy is not fed when there exists no liq. film as no electricity is energized. In addition, it is possible to heat effectively only the surface of the liq. film based on the surface effect by energizing an alternative electric current to the liq. film under high frequent or pulse condition. In addition, the steam 19 flows down and is returned into the lower container 24 after condensation as a falling down liq. film 22 in the vertical direction.