Particle wetting

In order to tailor the physical properties of nano-particles, wet granulation was conducted. Hydroxypropylecellulose (HPC-L) 5% aqueous solution was sprayed onto nano-sized Ti02 particles through a binary nozzle. Fluidization air velocity was set at approximately 1.5 times as large as the minimum fluidization air velocity. 

Figure 5.14. Two-dimensional Wulff metal particle wets the surface when the...

Wetting agent friction, mold release Improve particle wetting by liquid, aid dispersion... 

All products require a volume and velocity of air to break the cohesive bonds between particles, wet, or dry, and to permit the batch to become fully fluidized. Laboratory trials will yield values for process air volume for the various stages of the process. Using this volume and the dimensions of the product container, a face velocity through the distributor plate can be estimated (permeability of the plate is not considered). It is reasonable to assume that approximately the same velocity will be needed in scale-up. In Table 4, estimates for process air volume are derived from the cross-sectional areas of the base of the product container for various sizes of fluid bed dryers. 

Equation (7.11) is for the stick condition, i.e. when the solvent immediately adjacent to the spherical particle wets it and so moves along with it. Equation (7.12), on the other hand, is for the slip condition, i.e. when the spherical particle is completely slippery and does not drag along any liquid with it. When the spherical particle is an ion with charge z e and it is in the liquid under a potential gradient X (Vein ), a force/expressed by Eq. (7.13) operates on the particle ... 

At the first drying stage, the particle is isothermal and at the second drying stage the particle wet core temperature is different from that of dry crust. 

S. Heinrich, L. Mori, Fluidized bed spray granulation-A new model for the description of particle wetting and of temperature and concentration distribution, Chem. Eng. Proc.,... 

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