Vacuum

Vacuum

Vacuum Dryer

In vacuum dryer, material is dried by the application of vacuum. When pressure is lowered, the water boils at low temperature . Hence the evaporation is faster. The rate of drying is enhanced substantially.

Microwave Drying

·         It is the method of drying in which electromagnetic radiation (radio frequency from 3-150 MHz or microwave frequency at 915 or 2450 MHz) is applied to material dried.

·         If polar solvent molecules are present, the electromagnetic field induce orientation of the dipoles in molecules

·         As the field oscillates, the polar solvent molecules oscillate with the field, resulting in increased kinetic energy from dipolar molecules and their collisions with others

·         This manifested in thermal or heat energy

Applications

• Since the EM radiation penetrate entire granule and bed of granules, heating and vaporization of solvent can occur evenly throughout the mass
• Drying rates are proportional to rate of vapor diffusion rather than liquid diffusion
• Energy savings of 70% compared to fluid bed drying

 

Conclusion

The different drying equipments are available, but the suitable dryer is selected based on the Nature of material, cost, time and nature of the product required.