Moist Product, Movement of Moisture

The product contains moisture (usually water) mainly in the form of adsorbed liquid, capillary liquid, liquid causing the solid to swell or as bound liquid. Adsorbed liquid is a thin liquid film spread on the outer product surface. The vapor pressure above the liquid film corresponds to its saturation pressure at every temperature. Capillary liquid wets the inner pore surface of a porous solid. During the drying process, the liquid has to be transferred to the product surface by capillary forces. With products having macro capillaries of size 10 m, the vapor pressure still approximately cor- 

2 Pneumatic dryer with water-cooled jacket, first drying stage 

Common commercial 1. Spray dryer 1. Spray dryer l.T Spray 1. 1. Spray dryer 1. Spray dryer 1. Trough- Overflow  

For flat objects and endless films in the macroscopic range different kinds of baffle radiation dryers are used. 

Note (A) Common delivery form (B) Mostly obtained final form. 

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