Sewage sludge disposal for prodn. of useful material for cement mfr.

摘要

Sewage sludge is heated, after mechanical dewatering to about 50% total solids. The biomass is dried by flue gas at 150-180 deg C, continuously loosened in suspension, to be carbonised by indirect heating. The gas produced is burned and the heat used for drying, and to preheat air for carbonisation. The resulting carbonaceous, coked mineral mass is stored as a useful prod.. Also claimed is a plant for the process. It converts sewage sludge to raw cement grit. The dryer is a fluidised bed chamber (4) followed by an indirectly heated coking tube (6). The gases enter a combustion chamber (15) followed by heat exchanger (21) connected to the flue gas mixing chamber (25) for the fluidised bed (4).