Indirect Dryers Outdo Direct Dryers in Drying Applications

A 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 contact with a heated gas. These dryers are a critical component in many industrial processes, capable of processing all sorts of materials from chemicals & fertilizers to minerals & ores and nearly everything in between. 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 without opposing the gravity.

Rotary Dryers are extensively used for Drying but the following processes can be combined with it:

  • Cooling
  • Cleaning
  • Shredding
  • Separating

Features of Rotary Dryers:

  • Robust construction with various lifter (internal fins) options
  • Can be co-current or counter-current
  • Permits use of higher drying temperatures
  • Relatively long residence time
  • Highly efficient functions
  • Economic fuel and energy consumption
  • Low Maintenance cost
  • Reduced capital and operating costs
  • Huge capacity available as compared to other dryers

Rotary Dryers are majorly classified on the basis of heat transfer:

  1. Direct Rotary Dryer
  2. Indirect Rotary Dryer

Direct Rotary Dryers use direct contact between the material and drying air to scale down the moisture content of the material. Hot steam/air is circulated within the dryer, with the material being lifted up and rolled back down by a series of internal fins lined along the inner wall of the dryer. These dryers are used throughout a multitude of industries, including fertilizer and agriculture, mining and minerals, specialty chemicals, and more. They offer heavy-duty processing and consistent reliability.


But the direct dryers are at a disadvantage when assigned to dry material pigments or combustible materials as there is a risk of contamination or losing the original components of the materials. Hence the Indirect Rotary Dryers are brought into application. These dryers work on steam/air which is preheated by some means where burner combustion gases do not enter the dryer and have no direct contact with the material being processed. It commonly finds its application with food grade materials, highly combustible materials, organics such as grains and pulps, and fine materials such as pigments.
Rotary dryers can be widely used to dry various materials, and are simple to operate. They are used to process the following materials at the respective industries:

  • Metallic and nonmetallic minerals at Mining Industry
  • Sands, stones and soil at the Cement & Construction Industry
  • Wood chips at Wood Processing Industry
  • Food grains, cereals, pulses, seeds, fermented leaves at the food processing Industry

In some cases, combination of direct-indirect rotary dryers is also available to improve the overall efficiency.
Why choose us?
Accuracy, efficiency, machine quality and output quality are not just words but KERONE’s lifetime commitment towards our profession since last 42 years, creating a base of more than 1000 loyal customers. Our heating & drying systems are used to meet the varying demands of numerous industrial applications Рall with a level of precision that manufacturers seek. We also provide detailed assistance without much hassle of complex functioning of the machinery. We always strive to achieve more than client satisfaction with our timely delivery, quality and efficiency towards every machine manufactured by us.

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