Tunnel Dryer

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The tunnel dryer is the device used in the drying of the pharmaceutical materials like wet materials ,wet powdres or wet granules etc in to the free flowing materials.

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Description, Specifications , Principle , ansd Applications


The tunnel dryer is a modification of the tray dryer in which the oven is replaced by a tunnel which recieves damp materials at one end and dischagre the dried products at the other end.

It may be operated batch wise or continuosly. The tunnel dryer can be of any size and the movement of the solid materials can be affected by placing it on the trays on rails and at suitable intervals atray may be pushed into the inlet which displaces the tray from the dryed end. In the tunnel dryer to pass the materials the convyer belts are used and involves in the drying of the materials.


The tunnel dryer consists of

  1. Steam or electric heating air
  2. Cycling dry with heated air
  3. Proper temperature and drying tunnel


Its work principle is that used steam or electric heating air, then made a cycling dry with heated

air. There are even dry and lower discrepancy of temperature difference in the each side of oven.

In the dry course of suppling continuously fresh air and discharging hot air so that the oven. Might be in good condition and kept proper temperature and humidity.


  • Wet solid is introduced into the trays of the tunnel dryer.
  • Tray dryer are placed in the chamber.
  • Fresh air is passed in to the chamber through the inlet by the heater and the chamber get heated up.
  • The water is picked up by the dry air which is circulated in to the chamber of the funnel dryer.


  • It is widely used in pharmaceutical, food, chemical industry etc. which baked and dehumidified to material.
  • Tunnel dryer is used for industrial applications.
  • The performance of tunnel dryer for drying di-basic calcium phosphate like materials.
  • Tunnel dryers convey heated air and used in mainly the drying the wet material.


  1. C.v.s subrahmanyam et al., pharmaceutical engineering principles and practices-filtration, 2001.
  2. Mehta RM, Pharmaceutics-I: introduction to the drying process (1996), Page no: 187.

About the Author

Saraswathi.B's picture
Author: Saraswathi.B

Assistant Professor in St. johns college of pharmacy

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