Drying pasty materials e.g. sludge from treatment plant, by subjecting sludge exiting from mechanical dehydration by pressing to laying operation that is moderated to preserve structure of sludge present in outlet of mechanical dehydration

摘要

The process comprises subjecting sludge exiting from mechanical dehydration (3) by pressing to laying operation (4) that is sufficiently moderated to preserve a structure of the sludge present in an outlet of mechanical dehydration. A temperature of air in contact to the sludge in thermal drying step (5) is 75[deg] C. The laying operation comprises an operation of fragmentation of the sludge on a slab of installation of solar drying, and a transfer of fragmented sludge towards thermal drying in a solar drying installation, where the fragmentation step takes placed before heat drying step. The process comprises subjecting sludge exiting from mechanical dehydration (3) by pressing to laying operation (4) that is sufficiently moderated to preserve a structure of the sludge present in an outlet of mechanical dehydration. A temperature of air in contact to the sludge in thermal drying step (5) is 75[deg] C. The laying operation comprises an operation of fragmentation of the sludge on a slab of installation of solar drying, and a transfer of fragmented sludge towards thermal drying in a solar drying installation, where the fragmentation step takes placed before heat drying step. The heat obtained from the water evaporated by mechanical dehydration is collected in a heat exchanger (6) for thermal drying. The steam heat is recovered with condensation of evaporated water. The dryness of sludge in outlet of the mechanical dehydration step is 30 mass.% while the dryness of sludge from the drying step is 60-95 mass.%. The mechanical dehydration is performed under a partial vacuum. The thermal drying is performed under a partial vacuum to lower the evaporation temperature of the water. An independent claim is included for an installation for drying pasty materials.