page_title: Rotary dryer
section_title: Drum or shell variations
hierarchical_section_title: Rotary dryer / Drum or shell variations
caption_attribution_description: English: Double Shell Rotary Drum Dryer
context_page_description: The rotary dryer is a type 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.
  The dryer is made up of a large, rotating cylindrical tube, usually supported by concrete columns or steel beams. The dryer is inclined to 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 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 gas stream as it falls. This gas stream can either be moving toward the discharge end from the feed end, or toward the feed end from the discharge end. The gas stream can be made up of a mixture of air and combustion gases from a burner, in which case the dryer is called a direct heated dryer. Alternatively, the gas stream may consist of air or another gas that is preheated.
context_section_description: A rotary dryer can consist of a single shell or many, though any more than three drums is not usually necessary. Multiple drums can reduce the amount of space that the equipment consumes. Multi-shell dryers consist of several concentric tubes. Multiple shells allow the dryer to be utilized in a more compact space. The drums are often heated directly by oil or gas burners. The addition of a combustion chamber on the entry end helps ensure efficient fuel usage, and homogenous drying air temperatures. As the material moves through the rotating drum, it is heated, and moisture is released. Some dryers also offer the option to cool, clean, shred, and/or separate the dried material.
caption: Double Shell Rotary Drum Dryer
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