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FEECO's rotary dryers are custom designed for your specific processing needs. Whether you require low or high inlet temperatures, short or long residence times, counter-current or co-current flow, FEECO's design team can design a rotary dryer system for your application.
Many of our customers are not sure if a rotary dryer is the correct piece of equipment for their needs. FEECO offers a number of complimentary services up front to help you answer some of these questions:
Our experience base is vast and wide. We can offer cost competitive designs for pilot scale units that process as little as one ton per hour to heavy duty units in excess of 17 foot in diameter that process hundreds of tons per hour.
The rotary dryer, sometimes known as a rotary kiln, is a type of industrial dryer employed to reduce or minimize the moisture content of the material it is handling by bringing it into direct contact with heated gas. The dryer is made up of a large, rotating cylindrical tube, usually supported by concrete columns or steel beams. The dryer slopes slightly so that the discharge end is lower than the material feed end in order to convey the material through the dryer under gravity. Material to be dried enters the higher end of the dryer, and as the dryer rotates, the material is lifted up by a series of internal fins lining the inner wall of the dryer. When the material gets high enough to roll back off the fins, it falls back down to the bottom of the dryer, passing through the hot air stream as it falls. This air stream can either be moving toward the discharge end from the feed end (known as a co-current rotary dryer), or toward the feed end from the discharge end (known as a counter-current rotary dryer). The air stream can be made up of a mixture of air and furnace exhaust fumes (known as a direct heated dryer) or simply hot air (known as an indirect-heated dryer, which generally carries a lesser risk of causing product contamination).
The rotary dryer is also capable of calcining the material, or mixing two or more materials, and sometimes stimulating a reaction between two or more materials. The rotary kiln (as it is called when it is not being used to dry a material) is commonly used in the cement industry to cause a key reaction between two of its major components.
Typical material rotary dryers process include: aggregates, agricultural grains and by-products, animal feeds, animal waste, biosolids, ceramics, clay, fertilizers, gypsum, iron ore concentrates, limestone, metal chips and shavings, mining ores and concentrates, municipal sludge, municipal waste, organic and inorganic chemicals, paper sludge, plastic pellets, potash, reclaimed dust, rubber pellets, sales, sand steel mill waste / sludges, sugar urea prills and crystals.
In co-current rotary dryers, the heated drying air flows in the same direction as the product, and in counter current rotary models the drying airflow travels against the flow of the product. These rotary dryers directly expose the product to hot air produced by the heat source. As the drum rotates, lifting “flights” mounted on the inside of the drum shell tumble, slide, lift and shower the material into the air stream. Lifting flights are carefully designed to accommodate the material being dried and ensure the product is uniformly exposed. This agitation ultimately leads to higher efficiencies and reduces processing times compared to stationary units. It is not uncommon for a process taking 1 hour in a stationary furnace to take just a few minutes in a rotary dryer. A number of options for types of drying fuel and control methods are available including stand-alone microprocessor controllers or PLC controllers that directly interface with plant control systems.
This highly versatile new product from FEECO combines drying and cooling functions in a single installation utilizing injected air to produce a fluidizing action on the material. Additional internal indirect cooling can be used to help reduce the burden to the dust collection and exhaust system. This proven design can help solve problems encountered in installing a drying/cooling system in an existing space or building. The cooling hood section can be retrofitted to FEECO and competing brands of rotary dryers.