A pure steam generator having a feed line for conducting feed water thereinto, a heating steam input for conducting heating steam thereinto, and a heat exchange apparatus therein for providing heat exchange between the heating steam and the feed water. A pure steam output is also provided, with a separation space being located in a lower portion of the pure steam generator, along with a centrifugal separator through which the pure steam flows from the separation space to the pure steam output.The pure steam output communicates through a circulation line with the pure steam generator for circulating pure steam from the pure steam output to the pure steam generator. The circulation line is preferably arranged to feed a mixing space, in which the feed water and the circulating pure steam are mixed.