Method and facility for thermally drying pasty products
AssigneeSuez International
InventorPierre Emmanuel PARDO
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Abstract
Disclosed is a method for thermally drying pasty products, in particular wastewater sludge, and a belt dryer implementing such a method. The principle consists of partitioning the drying operations and using, for each of the successive operations, a different quality of air: (i) hot air for “searing” the sludge, (ii) low temperature air, then (iii) cold air for quenching the sludge before the extraction of same. Also proposed are loops of air supply circuits making it possible to optimize the energy consumption of the dryer by reusing energy produced within these circuits. Moreover, the loops make it possible to recover unavoidable low temperature energy or cheap energy, further optimising the consumption of the dryer.
Claims22
A method for the thermal drying of pasty products, particularly wastewater sludge, comprising:
- a step of depositing the pasty products on at least one conveyor belt (98), the depositing being performed in an inlet module (31),
- a step of moving the pasty products from the inlet module (31) as far as an outlet module (33), the moving of the pasty products being performed by moving the at least one conveyor belt (98, 99),
- a step of extracting the pasty products from the at least one conveyor belt (99), the extracting being performed in the outlet module (33),
- further comprising, during the moving step:
- a high-temperature drying step in which the pasty products are subjected to a high-temperature air flow (1) within at least one high-temperature drying compartment (34), then
- a low-temperature drying step in which the pasty products are subjected to a low-temperature air flow (10) within at least one low-temperature drying compartment (36), the low-temperature air flow (10) having a lower temperature than the high-temperature air flow (1), the low-temperature drying step occurring after the high-temperature drying step,
- further comprising, after the low-temperature drying step, a cooling step in which the pasty products are subjected to a cold air flow (15) within at least one cooling compartment (35), the cold air flow (15) having a temperature lower than the temperature of the low-temperature air flow (10),
- and wherein the pasty products are cooled using cold produced at an evaporator (14) of a heat pump (18) of which a condenser (16) is used to heat up one of the said air flows.
Dependencies are inferred from the claim text.