Drying equipment paddle dryers

For the first group the following types of dryers are generally used convective (tray, band, fluid bed, flash dryers, and their modifications) or contact (vacuum dryers such as double-cone dryer-blender, conical dryer with rotating helical mixer, paddle dryer). Pastelike materials are dried in tray dryers, band dryers equipped with extruding devices, and spin-flash dryers. Finally, thin pastes can be dried in spray dryers or on fluid beds or spouted beds of inert particles. Small amounts of solutions and suspensions are generally freeze-dried, especially if the product is thermolabile. 

Polystyrene (PS) and acrylonitrile-styrene (AS) are two other polymers produced in bulk quantities. Previously, these polymers were dried with FD. Later, C-FBD replaced all previous FD dryers because of their energy savings advantage. In recent years, paddle dryers have made rapid gains. The heat-resisting power of these materials is comparatively low. Melted material will adhere to the walls of the equipment if the processing temperature is not properly regulated. 

Chamber dryers equipped with stirrers are commonly used for drying of flotation concentrates (Figure 43.4). The dryer operates in a cocurrent mode. Hot combustion gases supplied to the dryer by a duct (5) meet at the outlet the cold and moist coal supplied by another duct (7). The dryer consists of a chamber (1) fitted with baffles (9) and two shafts (2) rotating in opposite directions on which paddles are mounted... 

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