Apparatus and method for purifying a liquid

For purifying a liquid, the liquid is caused to evaporate in a cyclone in a recirculation circuit. Vapor is discharged via a discharge channel in which a compressor is included. In a heat exchanger downstream of the compressor, supplied vapor condenses and heat thereby released is transferred to liquid in the recirculation circuit. A liquid inlet of the cyclone is placed and directed for delivering a jet having a directional component tangential with respect to an inner surface of the cyclone. The liquid inlet has a section shaped such that in operation the delivered jet is a flat jet having a cross section which in a direction parallel to a nearest generatrix of the inner surface of the cyclone is greater than in a direction perpendicular thereto. The jet contacts the inner surface of the cyclone before drop formation occurs in the jet. A method for purifying a liquid is also described.