Fluid Bed Coating

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DÜPERTHAL Sicherheitstechnik GmbH & Co. KG

During the process, the coating material is injected as liquid and the normally very dense and homogenous coating film forms immediately on the particle surface through a drying or solidification process. Fluid bed equipment is very frequently used to implement such applications. A fluid bed forms when a gaseous fluidization agent, air or nitrogen, flows through a bulk material so that the particles are fluidized and mixed intensively. The introduction of the liquid into the process chamber of the coating equipment by one or several spray nozzles can take place in different ways (Fig. 1).

Two Scenarios – One Common Goal

In the simplest scenario the liquid is sprayed from the top onto the fluid bed (Top Spray). By contrast, spraying from the bottom to the top (Bottom Spray) is also possible, especially with viscous spraying media and increased tackiness. Based on the above, an additional process variant has been developed where the particles are moved through the spraying zone in a controlled and uniform manner (Wurster Bottom Spray).

This is ensured through the integration of the inner partition around the nozzle as well as the use of specifically designed air distribution plate. This technique allows the application of very uniform coating layers with optimized quality.

There are different approaches to fluid bed coating but which one is the best for agien application? More on page 3!

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Fluid Bed Coating – Changing Properties of Solids as Desired

Two Scenarios – One Common Goal