Coater top spray

Fig. 3. Diagram of a Top Spray Coater. (Courtesy Glatt Air Techniques, Inc.)...

A more detailed overview of the development of continuous fluidised bed systems is covered in a review by Teunou and Poncelet (2002). Figure 16.7 shows a schematic diagram of a continuous top-spray fluid bed coater. 

Figure 372. Schematic representations of the product handling sections of three fluidized bed coaters. (a) Top spray, (b) tangential spray (rotary fluid bed coater), (c) bottom spray (Wurster coating system)...

Fig. 6.2-86 SEM photographs of particles that were coated with fluidized bed coaters a) coated with ethylcellulose in a top-spray fluid-bed processor, b) coated with ethylcellulose in a Wurster apparatus, c) vacuum top-spray coated (retard) pellet, cut open,...

Top spray. In the top spray system, the coating material is sprayed downward on to the fluid bed such that as the solid or porous particles move to the coating region, they become encapsulated. Top spray fluid-bed coaters produce higher yields of encapsulated particles than either bottom or tangential sprays. 

With the high demand for encapsulated materials in the global market, fluid-bed coaters have become more popular. They are used for encapsulating solid or porous particles with optimal heat exchange [105]. The Hquid coating is sprayed onto the particles and the rapid evaporation helps in the formation of an outer layer on the particles. The thickness and formulations of the coating can be obtained as desired. Different types of fluid-bed coaters include top spray, bottom spray, and tangential spray (Fig. 1.16). 

In the automated lay-up system, each layer of veneer (with exception of the top surface veneer) passes under an automatic adhesive appHcation system. This may be a spray appHcation, a curtain coater, or an extmder, each of which is designed to apply a uniform adhesive spread on the upper face of each veneer. After all except the top veneer have been spread with adhesive and laid together, the top veneer is added. The me of the veneer—adhesive assembly at this point should be about 8%. 

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