Process and equipment for drying sludges - with steam evolved in double-screw contact dryer, used to preheat the sludge in heat exchanger

摘要

De-watered sludge is heated in a heat exchanger to 70 to 80 degrees C before being taken to a double-screw contact dryer where it is dried by applied and evolved heat. The jacket of the dryer is heated to 120 to 250 degrees C by oil or steam, particularly by waste or exhaust steam. The steam evolved in the dryer is used for pre-heating the sludge. The equipment consists of a heat exchanger (1) below which is a dryer (2) which contains two rotating screws driven by a motor (5) and which is fitted with a heating jacket (11). The vapour evolved in the dryer (2) is conveyed by pipes (13) to the heat exchanger (1). The heating jacket (11) is connected by pipes (16,17) to a heating system (18). All of the equipment is mounted on a transportable frame. USE/ADVANTAGE - This invention is used for drying clarifier sludge, industrial sludge etc. The proposed system is energy efficient, a high degree of drying is achieved, and the equipment required is economical to construct.