In the pharmaceutical industry, a Rapid Dryer (also known as a fluid bed dryer) is used extensively to decrease the moisture content of medicinal powder and granules.

1. Process, Structure and
Working of A Rapid Dryer

2. • A Fluid Bed Dryer is designed for drying powders, crystals, and medium-sized pellets quickly and uniformly.
There are several uses for the Fluid Bed Dryer in the pharmaceutical and bulk drug industries as well as in dyes
and chemicals and Phyto-Chemicals.
• In the pharmaceutical industry, a Rapid Dryer (also known as a fluid bed dryer) is used extensively to
decrease the moisture content of medicinal powder and granules. Wet granules must be dried before
compression into a tablet may take place, as well as to adjust the viscosity and stickiness of the substance. As
the last step before compression into tablet form and packing, drying is usual.
• Perforated beds of wet solid particles are punctured by high-pressure hot air in the fluidization process. An
airstream is used to raise and suspend the dripping sediments from the tank's bottom (fluidized state). Direct
contact between the moist substance and the hot gases results in heat transfer. The drying gases pick up the
evaporated liquid and carry it away. Exit gas may be partly recycled in order to conserve energy.
• Drying wet grains, crystals, or coarse materials is made easier using the Fluid Bed Dryer. Passing high-speed
hot air through a bed of material to be dried causes it to become fluidized and so dries more quickly.

3. • The induced draught and fresh air are created by a blower on the dryer's exhaust side that uses no negative
pressure concept. From the bottom of the product container, a stream of heated, filtered air is emitted. The air
distribution plate and the Dutch sieve are included with this container. The turbulence in the product container
is created by passing the air stream through the bed of the substance. As a result of fluidization, heated air
surrounds each particle, causing rapid and even heating and drying. Particles can't escape the machine
because of the top-mounted filter bags.
• There is a good chance the ordinary person has never heard of them. Fluid bed dryers, on the other hand,
have made a name for themselves as versatile and trustworthy processing equipment in the bulk processing
industry.

4. The Pharmaceutics Industry's reliance on
Dryers
• Despite the fact that fluidized bed drying may be utilized in a wide range of sectors, pharmaceuticals have
perhaps benefited the most from its usage. It is possible to consistently reduce the moisture content of
pharmaceutical granules and powders by utilizing a fluid-bed drier. With the introduction of fluid bed drying
technology, drying periods have been reduced significantly and equal drying conditions have resulted in a
consistent finished product.
• Fluid bed dryers are ideal for drying a wide range of items, but pharmaceutical products in particular. The
system controls incoming air temperature to ensure that moisture evaporates off the granule's surface at the
right pace. A high input air temperature might lead to a surface crust that inhibits deeper moisture from being
transferred to the surface, slowing rather than speeding the drying process.

5. Principle of a Rapid Dryer:
• A perforated bottom of a vessel holding a bed of particle solids or wet granules allows high-pressure hot air
(gas) or ambient air to flow upward upwards better known as a fluid bed drier. The granules/particles stay
suspended in a stream of hot air because the velocity of hot air is greater than the settling rate of the
granules/particles. A fluidized state describes this state of affairs. Every granule/particle is thoroughly dried
by the heated air that surrounds it.

6. Structure
• Vertical and horizontal stainless steel or plastic FBD fluid bed dryer machines are available. Batch drying is
done in a vertical unit, whereas continuous drying is done in a flat unit. The material is loaded and unloaded
into a removable vessel at the dryer's bottom. The perforated mesh allows hot, high-pressure air to travel
through the vessel. The dry material is collected by placing bag filters on top of the tank.

7. Process:
• At the bottom of the dryer, a removable container holds the material to be dried. The hot air is brought up
through the prefilter and into the chamber through the heaters. The simultaneous operation of a fan is also
permitted. An increase in air velocity causes particles to move in a turbulent manner known as fluidization.
• All the while, the air stream is filled with very tiny granules and particles. When the frictional drag on the
granules/particles is equivalent to the force of gravity, a condition of pressure is attained. Due to the high
velocity of air, the particles are able to climb to the top of the air stream; this is known as fluidization.

8. Rapid dryer benefits include:
1. 2-8 times more efficient than a tray dryer
2. The drying capacity ranges from 5 to 250 kg per hour, depending on the model.
3. Granules/particles that flow freely are created.
4. It can also combine the material with great efficiency for the purpose of mixing it.
5. It may be used for both batch drying and continuous drying.
6. The removable vessel makes it simple to load and unload materials.
7. Tray and truck dryers can't keep up with the higher drying temperatures.