The rotary dryer is a form of industrial dryer employed to reduce or minimize the liquid moisture content of the material it is handling by bringing it into direct contact with a heated gas. A rotary dryer is reported to be of the direct type if by virtue of its design, heat is added to or taken from the solids by direct exchange between the gas and solids. The direct heat dryer are definitely the simplest and also the most economical class.
They are utilised whenever a direct exposure to the hot gas or air is not detrimental to the fed. When high temperature is required for rotary evaporator in a direct-heated rotary dryer, a combustion chamber is used and once low temperature is necessary on the other hand, for thermolabile materials, steam coil is utilized. Rotary dryer can be said to be indirect when the heating medium is separated from connection with the solid by way of a metal wall or tube.
Single Shell Rotary Drum Dryer – The dryer is comprised of a big, rotating cylindrical tube, usually backed up by concrete columns or steel beams. The dryer is inclined to slopes slightly so the discharge end is lower compared to the material feed end so that you can convey the fabric with the dryer under gravity. Material to get dried enters the dryer, and as the dryer rotates, the material is lifted up by several internal fins lining the inner wall in the dryer. Once the material gets high enough to roll back off the fins, it falls back to the bottom of the dryer, passing through the hot gas stream since it falls.
This gas stream either can be moving toward the discharge end through the feed end (known as co-current flow), or toward the feed end from the discharge end (called counter-current flow). The gas stream can be made up of a combination of air and combustion gases from a burner, in which case the dryer is called a direct heated dryer. Alternatively, the gas stream may include air or any other (sometimes inert) gas which is preheated. If the gas stream is preheated by some means where burner combustion gases do not enter the dryer, the dryer known as an indirect-heated type. Often, indirect heated dryers are utilized when product contamination is a concern. In some instances, a mixture of direct-indirect heated rotary dryers are also available to enhance the general efficiency.
A rotary dryer is acceptable to dry metallic and nonmetallic mineral, clay in cement industrial and coal slime in coal mine, etc. Rotary dryers could be widely used to dry various materials, and are easy to operate.
Rotary Dryers have numerous applications but are most commonly observed in the mineral industry for drying sands, limestone, stones and soil, ores, fertilizers, wood chips, coal, iron sulphate, filter cakes, sewage sludge, etc. Can also be applied on food industry mainly for liquids and for granular material such as food grains, cereals, pulses,coffee beans, fermented tea leaves, etc.
Drum or shell variations: Double Shell Rotary Drum Dryer. Triple Shell Rotary Drum Dryer – A rotary dryer can include one particular shell or many, though any more than three drums will not be usually necessary. Multiple drums can reduce the quantity of space that the equipment consumes. Multi-shell dryers include several concentric tubes. Multiple shells enable the dryer to become utilized in a more compact space. The drums are frequently heated directly by oil or gas burners. Incorporating a combustion chamber on the entry end helps ensure efficient fuel usage, and that homogenous drying air temperatures. As the material moves through the rotating drum is heated and moisture released. Some dryers offer the option to cool, clean, shred, or separate the dried material.
For evaporating moisture from concentrates or some other products from plant operations, Rotary Dryers are created and constructed for high efficiency and economy in fuel consumption. Anytime you can to apply heat direct for the material to be dried, Rotary Dryers of the Direct Heating Design are used. When it is difficult to use heat direct towards the material to be dried, Rotary Dryers from the Indirect Heating Design could be furnished in order that the heated gases is not going to come in direct exposure to the material.
Rotary Dryer is an easy, inexpensive unit for lowering the moisture content of flotation concentrates, along with chemical and industrial products. Frequently the saving of shipping weight so effected pays tjihbx the dryer in a couple of months. Difficulties from freezing while in transit can also be eliminated. Many industrial projects are now using Dryers for control and production purposes on many materials.
Three main types of rotary evaporator can be supplied. The direct heat unit can be used when it is permissible for the drying gases ahead in direct contact with the content being dried. Partition plates increase the heating surface. Drying might be by hot air or exhaust gases off their operations. If this type of drying gas includes a deleterious effect on the product, then an indirect type of dryer may be supplied. An additional derivation will be the Tedrow Steam Dryer.
The movement in the material is due to combined effect of inclination in the shell towards the horizontal and the internal tumbling action or mechanical turn over thus the name tumbling dryer. The type in the feed determines the directions of gas flow through the cylinder in fact it is relative to the solid. This drying equipment can also perform batch or continuous processing from the wet feed.