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.
Claims11
A dryer, comprising:
- an inlet module (31) for supplying an upstream end of a treatment path with pasty products;
- at least one conveyor belt (98, 99) allowing the pasty products to be received at the upstream end of the treatment path and moving them along the treatment path;
- an outlet module (33) allowing the pasty products to be extracted at a downstream end of the treatment path;
- behind the inlet module (31) along the treatment path, at least one high-temperature drying module comprising at least one high-temperature drying compartment (34) and at least one high-temperature circuit, the at least one high-temperature circuit being able to generate a high-temperature air flow (1) within the at least one high-temperature drying compartment (34);
- between the high-temperature drying module and the outlet module along the treatment path, at least one low-temperature drying module comprising at least one low-temperature drying compartment (36) and at least one low-temperature circuit, the at least one low-temperature circuit being able to generate a low-temperature air flow within the at least one low-temperature drying compartment (36), the low-temperature air flow having a temperature lower than the high-temperature air flow (1);
- means for cooling the pasty products leaving the low-temperature drying compartment (36) using cold produced by an evaporator (14) of a heat pump (18);
- and
- at least one low-temperature hot-water circuit (6) in which there circulates water for heating the low-temperature air flow,
- wherein the water circulating in the at least one low-temperature hot-water circuit (6) is heated by at least one condenser (3).
Dependencies are inferred from the claim text.