Tray dryers

A tray dryer is a type of batch drying equipment used to remove moisture from solids by circulating hot air over material placed on trays. It is widely used in industries such as **Pharmaceutical Industry, Food Processing Industry, and Chemical Industry.

1️⃣ Construction of a Tray Dryer

Main parts include:

1. Drying chamber

   • Insulated cabinet where drying occurs.

2. Trays

   • Shallow metal trays where wet materials are spread.

3. Heating system

   • Usually electric heaters or steam coils to heat the ai

     1. • r.

     2. Blower/Fan

        • Circulates hot air uniformly over the trays.

     3. Air inlet and outlet

        • Fresh air enters and moist air exits through vents.

     4. Temperature controller

        • Maintains required drying temperature.

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     2️⃣ Working Principle

     Tray dryers operate on hot air convection drying.

     Steps:

     1. Wet material is spread evenly on trays.

     2. Trays are placed inside the drying chamber.

     3. Hot air is generated by heaters.

     4. A blower circulates hot air over the trays.

     5. Moisture evaporates from the material.

     6. Moist air leaves through the outlet vent.

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     3️⃣ Typical Operating Conditions

     • Temperature: 40°C – 120°C (depends on material)

     • Drying time: Several hours

     • Airflow: Forced convection using a fan

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     4️⃣ Applications

     Tray dryers are used for drying:

     • Pharmaceutical powders and granules

     • Fruits and vegetables

     • Chemicals

     • Herbal products

     • Pigments and dyes

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     5️⃣ Advantages

     ✔ Simple design
     ✔ Low installation cost
     ✔ Easy to operate
     ✔ Suitable for small-scale production

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