What is a Fluidized bed dryer?

A fluidized bed dryer is used in the oral solid dosage section of the pharma industry to reduce moisture content before advancing to its next stage. Learn about Fluidized bed dryer and their various components.

A fluidized bed dryer controls the moisture content in the powder mixture of the oral solid dosage form. It utilizes a different heating mechanism for moisture reduction in a product to acceptable limits per the product or process requirement. The moisture content is continuously monitored during drying, and drying is stopped when it reaches the desired value.

A fluidized bed dryer is a  standard equipment in the pharmaceutical industry, typically in the Oral Solid Dosage section. It is used to process powder having high moisture quantities before advancing to its next stage of forms, such as Oral Suspension or tablet compression.

Fluidized bed dryer principle

Fluid Bed Dryer works on the principle of fluidization of particles; that’s the reason for the name fluid. It means making solid particles behave like a fluid by using external factors and forces. In the FBD, fluidization is achieved by passing high-speed air from the bottom of the product container. The high-velocity air pushes the powder upwards and makes them suspend like fluid.

Fluidization in solid particles enables the production personnel to apply parameters and phenomena not possible in solid bulk form. It increases the ability of solid particles to react to external factors more efficiently and effectively. It also helps to consume fewer resources and time in a process that would be in a solid stage.

Fluidization in FDB increases the exposure of powder particles to heat. Individual powder particles can react rapidly and promptly. This produces uniform heating throughout the bulk material without the risk of localized evaporation, heating, and product damage.

Working of a Fluidized bed dryer

The working of a typical fluid bed dryer can be described as follows

The material to be dried is transferred in a container called a product container or trolley. The bottom of the product container is mesh, providing air passage through it.

When air passes from the bottom at high speed, it suspends the particles in the air. The temperature of the air is elevated to facilitate the drying process.

The heat exchange method reduces the moisture content as the hot air comes in contact with the moist powder. The moisture content reduces further as the interaction with the powder and heat increases.

The material is frequently checked for moisture content to prevent under or overheating. When moisture content reduces to the required levels, FBD is stopped. The remaining powder is taken out by pulling the container or trolley out.

Fluidized bed dryer Equipment

Fluid Bed Dryer consists of various parts designed for a specific function. These individual parts contribute to the overall working of FBD equipment. Its working can become erratic if any of them fails to perform its particular function.

Some common parts include the following.

Air Handling Unit

The air handling unit conditions the air supply to the fluid bed dryer by altering different air properties such as temperature, humidity, and velocity. This conditioned air passes through the product in a product container. The air handling unit is connected to the FBD through ducting.

Air flows into the AHU with the help of blowers. Air passes through the heating, cooling, and filter section. The heating and cooling sections set the desired temperature, while the filter section cleans the air. Filtration is necessary because this air comes in direct contact with the powder, which becomes the basis of pharma products.

The conditioned air from the AHU flows through the ducting into the fluid bed dryer.

Inlet Plenum

The inlet plenum is the part of FBD that extends to the FBD bottom. It is used to connect AHU with the FBD. In some cases, process instruments are installed on it, like temperature and air velocity

Bottom part

The bottom part is used to house the product container. It is attached and fixed to the base of FBD and connects to the inlet plenum. Air from AHU enters the bottom part and then the product container. A mesh is installed at the bottom of FBD to regulate the airflow into the product container.

Product Container

A product container is a large metallic structure that contains the powder to be dried. The air from AHU passes through the product container, which heats the product inside it.

Process instrumentation is also installed on the product container for process monitoring. This instrumentation provides real-time data on the product inside the container.

Upper Part

The upper part is the extension of FBD on the top of the product container. It consists of filter bags to collect powder and prevents powder from escaping into the air through exhaust.

The automatic system shakes the filter after a preset time. The main reason is to shed particles from filter bags that have accumulated on them.

Outside Plenum

The outside plenum connects the upper part of FBD with the AHU (through ducting). Process instruments and sensors can also be installed to monitor the air flowing from the product into the exhaust, which can then be used for process understanding.

Frequently Asked Questions – Fluidized bed dryer.


How does a fluidized bed dryer work?

A fluidized bed dryer works by suspending the solid powder particles in air and applying a heating mechanism to dry them.

What is fluidized bed principle?

Principle of a fluidized bed is the fluidization technique, in which solid powder particles behave like fluid by the action of high velocity supply air.

Why is it called fluidized bed?

It is called a fluidized bed because a high velocity air supply causes the solid powder to flow like a fluid. The bulk quantity of powder makes it happen like a flowing bed.

What are the components of a fluid bed dryer?

Common components of fluid bed dryers are






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