Fluid bed drying: so that particles dry quickly and gently

This is what happens in so-called spray drying: moist particles are heated and dried in a controlled manner in the fluidized bed. Water or organic solvents evaporate.

Today, fluid bed drying is used in all powder processing industries. In the pharmaceutical industry, the innovative process has long since replaced the time-consuming process in tray dryers or drying ovens.

This is how the drying process in the fluid bed works

• fast: The drying time – compared to the drying oven – is reduced by a factor of about twenty; due to the intensive heat or moisture exchange of the fluidized product, drying in the fluid bed system is particularly effective and time-saving.
• controlled and gentle: Unlike uneven drying in tray dryers, spray drying offers homogeneous drying conditions; water or organic solvents evaporate in a controlled manner.

Fluid bed drying at Glatt: in thermodynamic equilibrium

What are your product quality requirements, how high should the residual moisture of the particles be? Good to know: Our technology is also suitable for post-drying spray granulated or extruded products with very low residual moisture.

Regardless of how the particles were generated – in the fluid bed, in the compulsory mixer, in the batch or continuously – with fluid bed drying it is all about the right application:

• As a matter of principle, we make sure that drying takes place in thermodynamic equilibrium.
• We select the supply air temperature exactly so that only as much moisture evaporates from the surface of the granules as is transported out through the capillaries from inside the granules.

Caution with too high supply air temperatures

If supply air temperatures are too high, surface crust formation must be expected. The removal of moisture from deeper layers is impeded or even prevented, and the entire drying process is delayed.

Note on the process variants spray granulation, spray agglomeration and spray coating: Not only does moisture evaporate up to a defined residual value, but drying also takes place during the entire spray process. Excessively high supply air temperatures can therefore lead to insufficient liquid bridges, unstable granulate structures or inhomogeneous-looking films.

Your advantages with fluid bed drying

Used correctly, it offers you an efficient solution for fast, gentle and uniform drying of moist solids.