An apparatus for treatment of process vapours coming from a vacuum concentration section of a urea plant, comprising a vacuum system having a plurality of successive condensation stages, connected in series by respective line portions and crossed in series by process vapours to be treated; the apparatus has at least one primary steam condensate inlet for feeding steam condensate to the vacuum system and positioned, with reference to a circulation direction of the process vapours in the vacuum system, upstream of at least one selected condensation stage, or in at least one selected condensation stage.