Question

For drying of heat sensitive materials, this particular type of dryer is used

• A. Tray dryer
• B. Vacuum dryer
• C. Tunnel dryer
• D. Drum dryer

Hint:

When working with heat-sensitive materials, opt for vacuum drying as it minimizes thermal damage by reducing the drying temperature.

Answer 1

The Correct Option is B

Step 1: Understanding the need for a specific dryer.
Heat-sensitive materials require a drying process that minimizes exposure to high temperatures. Vacuum dryers are commonly used for this purpose because they operate under reduced pressure, lowering the boiling point of solvents and thus preventing thermal degradation.
Step 2: Analyzing the options.
(A) Tray dryer: While tray dryers are commonly used, they expose materials to higher temperatures, making them unsuitable for heat-sensitive materials.
(B) Vacuum dryer: Correct — Vacuum dryers reduce the temperature required for drying by creating a vacuum, making them ideal for heat-sensitive materials.
(C) Tunnel dryer: This dryer uses continuous flow of air and may not be appropriate for materials sensitive to heat.
(D) Drum dryer: Drum dryers involve direct heat transfer and are not ideal for heat-sensitive materials.
Step 3: Conclusion.
The correct answer is (B) Vacuum dryer as it is specifically designed for drying heat-sensitive materials.

Answer 2

The choice of dryer for heat-sensitive material comes down to which option can remove moisture without exposing the material to high temperature, so we can test each dryer type against that requirement using the physics of drying.

1. Tray dryer: A tray dryer relies on hot air circulated at atmospheric pressure to evaporate moisture, which typically requires higher temperatures to be effective, exposing the material to heat it may not tolerate.
2. Vacuum dryer: Reducing the pressure inside the drying chamber lowers the boiling point of the solvent in the material, allowing moisture to evaporate at a much lower temperature than it would at atmospheric pressure. This lets heat-sensitive materials be dried gently.
3. Tunnel dryer: This design moves material through a heated tunnel via conveyor and still depends on convective heat at atmospheric pressure, similar in principle to a tray dryer, so it carries the same heat-exposure risk.
4. Drum dryer: A drum dryer applies material directly onto a heated rotating metal drum, which involves direct, often intense, contact heat - the opposite of what a heat-sensitive material needs.

Only reducing pressure to lower the evaporation temperature satisfies the heat-sensitivity requirement.

Therefore, the correct answer is Vacuum dryer.