A liquid cleaning device comprises a vessel (1), a bottom plate (3), a heating device and a tubular riser (12) arranged in the vessel for heated liquid ascending through the riser, the heated liquid from the upper, open end of the riser running back through force of gravity down and outside of the riser to be reheated and ascend agains through the riser, and so on. The vessel--61) is cylindrical and substantially its entire base (17) can be heated by means of the heating device (171). A plurality of discs (51 54) of equal size are arranged in the upper part of the vessel (1), said discs having a central aperture (510) for the riser (12) and a plurality of small holes (511) distributed uniformly across the entire surface of the discs and provided with drip edges (5110). A distributor (14) is arranged at the upper, open end of the riser (12) to distribute the hot liquid coming out of the ruser uniformly over the uppermost disc (51).