Rotary Dryer

Rotary cascade dryers have the feed materials pass through a rotating cylinder together with a stream of hot gas. Internal lifters or flights elevate the feed and drop it in a curtain from the top to the bottom cascading along the length of the dryer. Flights need to be carefully designed to prevent asymmetry of the curtain. Material moves from one end of the dryer to the other by the motion of the material falling due to the angle of inclination of the drum. Some rotary dryers are double and triple pass units where each drum is nested inside the previous drum.

Rotary louver dryers have the feed materials supported and moving over a set of louvers mounted to an external rotating drum. The hot gas is introduced into a tapered bustle below the feed ring. The air passes through the louvers and then the product before being exhausted from the dryer.

The rotation of the drum causes the material to roll and mix providing intimate contact with the drying gas. Material moves from one end of the dryer to the other by the motion of rolling, some fluidization and due to the angle of inclination of the drum.

• Buildings & Constructions
• Minerals & Ores
• Food products
• Soil remediation
• Chemicals
• Pigments
• Starch Products
• Pesticides and fertilizers
• Pond ash to fly ash
• Saw Dust
• Salt Dryer
• Many Other Drying Applications
• Sands, Limestone’s, Stones and Soil, Ores, fertilizers, wood Chips, Coal, Iron-sulphate, filter cakes, sewage sludgeEtc…

The dryer is widely used for drying materials in the industries of cement, mine, contraction, chemical, food, compound fertilizer, etc. Feeding and discharging unit is installed with thermocouple to control drier temperature. The temperature change of drier’s feeding end can be indicated by the thermometer to control the inner drier temperature (generally 250-350o)

This dryer adopts direct flow type of heating with heat source from firing unit. The material to be dried is pushed back immediately by spiral board when enters the shell from feeding tank and feeding chute. Because the drier is installed in slope, material flows to the back end under gravity and rotation force, meanwhile, it is lifted by board repeatedly and thrown down accordingly, which make the material form even curtain, and exchange heat sufficiently with inner the heat flow. In the end, water in the material is dried by repeatedly scattering.

Automatic and continuous. Vibrators, screw feeders, rotary airlocks, double flap valves, gravity chutes

Powders, granules, non-friable agglomerates, large solid particles. Low to high feed rates

Steam, electrical, coal, liquid fuels, or gas

Mostly Direct. Flow is co-current or counter current for cascade dryers. Flow is a combination of through the bed, cross, co-current or counter current for rotary louvers. Residence time Controllable. Residence time can be altered by varying the speed of rotation of the drum and the drum angle. Fill can be varied. Fills are typically between 7% and 25% of the cross sectional area of the drum.

Normally induced. Systems can have combustion, forced and induced draft fans for operation.

Cyclones, bag houses, scrubbers, Electrostatic precipitators. Systems require dust collection.

PLC, infrequently solid state controllers. System controls on discharge temperature. Can modulate energy and feed.