Principle of Fluidized Bed Dryer

A fluidized Bed dryer known as its nickname FBD is a machine used in the granulation section of the tablet’s manufacturing area. In this article, we will learn the principle of fluidized bed dryer and its importance in the pharmaceutical formulation industry. FBD is used to dry wet material in the granulation section. In this machine, the required moisture content can be achieved to find the best compression properties in granules for tablets. FBD is used to get fast and accurate granulation in the granulation area, this machine saves lots of manpower by its automated capabilities.

Principle of Fluidized Bed Dryer
Principle of Fluidized Bed Dryer

Principle of Fluidized Bed Dryer:

When the air is introduced upside down with a velocity more than the velocity of particle settling, then the solid particles start to blow up and sustain in the air stream. This stage makes the solid bed boiling liquid. Thus the process is called fluidized. The drying rate of the material depends on the temperature of the air used for fluidizing the bed.

The FBD is made with a stainless steel chamber. The SS chamber has a perforated bottom that can be easily removed, that is called a bowl. The bowl is the container where materials are kept for drying. The bowl is designed in such a manner that hot air can be introduced from its bottom. The temperature of the air can increase or decrease from heaters installed there.

The air entering the bed of material is pre-filtered. The air passed through the bed should be clean and free from any foreign particles. The air is produced by different fans fitted on the equipment. These fan speeds can be adjusted from the control panel so that the flow rate can be regulated.

When the hot air is passed through the FBD bag at high speed the bag expands like a balloon. The particles of powder present inside start moving in turbulent motion. Direct contact of hot air to the particles makes them dry very soon. So the FBD process is very time-saving. 

The air leaving for FBD passes through some special size filters to avoid going the particles in the atmosphere. Flowing particles are collected inside of FBD. 

Benefits of Fluidized bed Dryer

A fluidized bed dryer is a high-potential machine that can dry material at an accelerated rate in a short span of time, this machine is not only used for drying the material but also for making granules of uniform size. The uniform size of granules helps to manufacture good quality tablets in terms of dissolution and finishing. 

The structure of FBD bags is like human fingers that allow maximum surface area to the drying material at the time of airflow. The increased surface area increases the drying rate of the material. 

Summary:

The operation of a fluidized bed dryer should be done by a trained and qualified operator. There are very high chances of catching fire from drying material due to the development of electrostatic charge. When the outlet filters get blocked the chances of fire increase. When the outlet filters get blocked the pressure inside of FBD increases which can lead to fire or mechanical breakage of the FBD chamber. Always operate FBD according to SOP for a Fluidized-Bed dryer.

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