Patent ID: 8832962

Claim:
A method for drying slurry-like materials, in particular of sludge from wastewater treatment plants, the method comprising: drying in a first drying stage ( 2 ) of an indirect type, supplied with hot fluid, which receives sludge having an entry dryness Se, and outputs sludge having an intermediate dryness Si and water vapor, which is channeled toward a condenser ( 8 ) in order to reheat there a loop for heating fluid, in particular water; forming strings of sludge at the exit from the first stage; and drying in a second drying stage ( 6 ), in which the strings of sludge are heated directly by a gas, the gas being heated by the heating fluid loop, this second stage ( 6 ) outputting a product having a final dryness Sf, wherein the intermediate dryness Si is controlled according to the measured entry dryness Se and the desired exit dryness Sf, for minimum consumption of the total energy used for the drying, the flow rate, pressure and/or temperature of the hot fluid ( 3 ) supplying the first drying stage ( 2 ) being adjusted accordingly.