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Renin Angiotensin Mechanism.

Drum Dryers.

 

Definition

  • Drying is defined as the removal of liquid from a product usually with application of heat.

  • Equipment used for the purpose of drying are called “Dryers”.

Drum Dryers.

  • Also known as: Roller Dryers, Film Dryers.

Principle:

  • It's an indirect type, continuous moving bed dryer.

  • The suspension or slurry to be dried forms a thin layer around the surface of the roller and gets dried.

  • Suitable for solutions with thick consistency.

Construction:

  • It consists of one or two horizontally mounted hollow drum(s) made of high grade cast iron or stainless steel, a supporting frame, a product feeding system, a scraper, storage bin or conveyors, drum speed regulator and other auxiliaries. 

  • Typical structures of gle and double drum dryers are as shown in following diagram. 

  • The diameter of typical drums ranges from 0.5 m to 6 m and the length from 1 m to 6 m.

Working:

  • The liquid to be dried is placed in a shallow pan.

  • The hollow rotor is mounted in the shallow pan with liquid.

  • As the rotor starts to move the liquid forms a thin film on the surface of the rotor.

  • The rotor can be heated by passing steam inside the rotor.

  • The liquid forming film gets dried quickly, the process can also be fastened by blowing air on the film.

  • The film is spread uniformly with the help of a spreader attached to the assembly.

  • The dried product is scrapped by using a scrapper.

  • The product is collected in a product bin.

Uses:

  1. Used to dry the products of thicker consistency.

  2. e.g.

    1. Milk products.

    2. Kaolin.

    3. Antibiotics.

    4. Yeast.

    5. Barium carbonates etc.

Advantages:

  1. Less drying time.

  2. Useful for thermolabile substances.

  3. Occupies a lesser place.

Disadvantages:

  1. Higher investment.

  2. Higher maintenance cost.

  3. Skilled operators needed.

Commonly Asked Questions.

  1. With a well labelled diagram describe construction and working of Drum Dryers.

  2. Write a short note on the Drum Dryer.
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