Method and facility for drying slurry-like materials, in particular sludge from wastewater treatment plants

Abstract

The invention relates to a method for drying slurry-like materials, in particular sludge from wastewater treatment plants, including two drying stages, namely: a first indirect drying stage (), supplied with hot fluid, which receives sludge having an entry dryness Se, and outputs sludge having an intermediate dryness Si and water steam, which is channelled towards a condenser () in which a heating fluid, in particular water, is reheated and, in turn, heats a heating gas for a second drying stage (); and a step () of forming strings of sludge at the exit from the first stage; the second stage () of drying the strings of sludge using gas at least partially heated by the heat extracted from the condenser, said second stage outputting a slurry having a final dryness Sf; 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 drying, the flow rate, pressure and/or temperature of the hot fluid () supplying the first drying stage () being adjusted accordingly.