Hot air dryer Direct

convectionconductionrotary

GRELBEX direct rotary dryers enable the industrial drying of any powdered solid by directly exposing the product to hot gases. They are designed to guarantee reliable operation, high efficiency, maximum industrial availability, and low maintenance. These performance criteria make our rotary dryers a smart choice for drying powdered solids. OPERATION Direct rotary dryers consist of a cylinder (called a "drum" or "calender") that rotates slowly and steadily on two supports (called belts). This cylinder is driven by an electric or hydraulic motor. - The rotating drum is slightly inclined and rotates continuously, ensuring uniform mixing and advancement of the solid product by gravity alone. - Drying is continuous, allowing for the processing of both small and large volumes (several tens of tons per hour). Heat Transfer Method - Heat transfer occurs either by direct convection (hot gases in contact with the product) or by indirect conduction (heat transmitted through the drum wall). - This choice depends on the product's sensitivity. For example, mineral products are often less fragile and can withstand direct contact with heat. Organic products are often more sensitive and must be treated with indirect dryers. ADVANTAGES - Wide temperature range (from 100°C to over 400°C depending on the process). - Suitable for a variety of products: powders, granules, slurries, crystals, chips, etc. - Can operate under specific atmospheres (air, nitrogen, vacuum, steam). - Mechanically robust construction, low susceptibility to fouling, and easy to maintain. - Stable operation, moderate operating costs, and long service life. It should also be noted that these dryers are integrated into thermal processes that must be optimized. Numerous options exist for recovering energy from the drying airflow after the process (recycling, condensation, cooling, separation, etc.). This allows for the overall optimization of the installation's operation. APPLICATIONS: Mineral Industry - Drying of sands, gravels, clays, kaolin, silica, lime, cement, gypsum, dolomite, bauxite, etc. - Drying of mineral powders before storage or transport. Advantage: continuous operation and homogeneous processing of a mineral (with variable moisture content) to improve handling, grinding, and final quality, or to allow for separate curing. Chemical Industry - Drying of chemical crystals, powders, and granules: fertilizers (urea, ammonium, phosphate), salts, carbonates, sulfates, oxides, pigments. - Drying of hygroscopic or viscous products (resins, polymers, catalysts). Advantage: rotary dryer ensures homogeneous drying, even for sticky or heterogeneous products. Waste Treatment - Drying of sewage sludge before incineration, composting, or energy recovery. - Pre-drying of solid industrial waste before pyrolysis, gasification, or co-incineration. - Drying of activated carbon, biochar, or biomass after thermal treatment. - Preparation of biomass for the production of pellets or biofuels. Advantage: Reduces volume, improves the lower heating value (LHV), and facilitates transport.