Abstract: In a process for drying a substance, particularly wood shavings, wood chips or wood flakes, a partial stream of the vapor-gas mixture is separated after passing through the drying drum before the vapor-gas mixture is led to a first heat exchanger. This separated partial stream is led through a supplementary heat exchanger before it is conducted into the combustion chamber of the furnace in which combustion takes place of the gases arising during the drying. The flue gases are led through the aforementioned supplementary heat exchanger before they reach the first heat exchanger whereby they are brought down to a lower temperature. In this way the thermal stress on the material of the heat exchanger elements of the first heat exchanger is reduced, thereby increasing the life of these heat exchanger elements.