Method for operating a drying device

A method for operating a drying device comprising at least a first and a second chamber provided with bottoms for bulk material to be dried, and means for supplying to each chamber and discharging from each chamber a gaseous medium, wherein the bulk material, after being partially dried by means of said gaseous medium, is transported from the first chamber to the second chamber, characterized by

• providing the gaseous medium to each chamber, the gaseous medium carrying energy into each chamber thereby to cause energy to be given out by said bulk material,
• determining an energy increase for each chamber brought about by:
• the energy supplied to the chamber by means of the gaseous medium and
• the energy given out by said bulk material,
• determining the amount of moisture that has evaporated from the bulk material in each chamber on the basis of the energy increase, and
• determining the amount of moisture expected to be present in the bulk material discharged from the device on the basis of the difference between the amount of moisture present in the bulk material introduced into the device and the sum of the amounts of moisture that has evaporated in said chambers.