Evaporation dryer and method for operating same

An evaporation dryer for the drying of particles, comprising:

• a process chamber having at least one product inlet for feeding of particles to be dried into a process chamber space and having a product outlet for evacuation of dried particles from the process chamber;
• a heat exchanger arranged within the process chamber, the heat exchanger comprising
• at least one inlet for highly pressurized steam as heating steam and at least one condensate outlet connected to an expansion tank,
• wherein the expansion tank is connected to at least one pump which pumps off flash steam from the expansion tank and supplies the flash steam to the heating steam,
• wherein the heat exchanger is of multi-stage construction having at least a first stage and a second stage,
• wherein to the first stage comprises a mixed steam of the heating steam and the flash steam, and
• wherein the second stage is configured such that the heating steam is fed to the heat exchanger.