Why are FBD Bags (Fluid/Fluidized Bed Dryer Bags) used?

During the process of formulation of tablets there are various stages involved. In the granulation area of pharmaceuticals drying is one of those vital stages in manufacturing of OSD(Oral Solid Dosage) drugs. The drying process strives to attain the desired moisture content in the granules. These granules are the core material that are later converted into tablets through tablet compression. FBD(Fluid Bed Dryers/ Fluidized Bed Dryers) machines in granulation area are used for this purpose of drying the particles by using fresh hot air current.

The FBD machines comprises a stainless steel removable bowl in the bottom. The material to be dried is placed in the blow and air is passed through the inlet and heated at required temperature gradually. Use of hot air increases the drying rate of the material. The air is allowed to flow in the upward direction with velocity higher than the settling velocity of the granules which enables the particles placed in the blow to ascend and suspend in the air stream within the chamber. Later these particles fall down in a random boiling motion. This stage is called the fluidized stage as the whole process seems like a container filled with boiling liquid, hence the name Fluidized Bed Dryer. During this process water and other liquid solvents are removed from the granules.

There is continuous flow of hot air into the blow which enables the particles to remain suspended in the air stream and get dried at a faster rate. There is an outlet that allows the air to pass but retaining the material is very important hence FBD bags (known as bed) are used as a filtration surface/media. The air passes through the FBD bags and it expands, the powdery particles get retained within the FBD bags. The particles retained in the inner surface of the bag is collected by shaking of the bag periodically.

The finger like structure ultimately increases the surface area of the drying bed. This increase in the area helps to improve the drying rate and reduce the drying time of the material. Therefore this structure of the dryer bag enhances the optimality of the whole process. The drying process in FBD depends on the MOC (material of construction) of the bag and Khosla Profil assures you to provide with the best quality material to get effective results in your drying process.

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