An apparatus for stripping and strengthening and subsequent condensing and final strengthening of an easily vaporizable component of a preferably aqueous mixture permits the heat necessary for stripping and strengthening to be transferred through a common heat transmission body (3), where the heat is derived from condensing the vapor generated by stripping and strengthening, which vapor via compression using a heat pump (26) has obtained the increase in boiling point necessary for condensation. The apparatus is comprised of two sections, namely a stripping and strengthening section or first section (1) and a condensing and final strengthening section or second section (2), said sections being joined around a common heat transmission body (3) forming a dividing wall, each section being further defined by a horizontal partially cylindrical housing (13) and an end wall at each end. Each of the sections is provided with an atomizing rotor (4) adapted to throw liquid from each side from the bottom of the horizontal partially cylindrical housing (13) inward against the common heat transmission body, an axial liquid channel (5) providing a continuous passage of liquid through the apparatus extending along the bottom.