Batch Rotary Dryers

In a batch rotary dryer, a horizontal cylinder is used to contain the batch while heated air is passed across the length of the cylinder. A jacket can be placed on the outside of the cylinder where steam or hot water is introduced to aid in heat transfer via conduction through the walls. Sometimes an agitator shaft with paddle arms, either heated or unheated, are included in the design to assist in heat transfer and product discharge. 

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Design Methods for Batch Vacuum Rotary Dryers The rate of heat transfer from the heating medium through the diyer wall to the sohds can be expressed by... 

Performance and Cost Data for Batch Vacuum Rotary Dryers Typical performance data for vacuum rotaiy diyers are given in Table 12-26. Size and cost data for rotaiy agitator units are given in Table 12-27. Data for double-cone units are in Table 12-28. 

Figure 9.4. Types of dryers cited in Tables 9.1 and 9.2. (a) Tray or compartment, (b) Vacuum tray, (c) Vertical agitated batch vacuum drier, (d) Continuous agitated tray vertical turbo, (e) Continuous through circulation, (f) Direct rotary, (g) Indirect rotary, (h) Agitated batch rotary (atmos or vacuum), (i) Horizontal agitated batch vacuum drier, (j) Tumble batch dryer, (k) Splash dryer. (I) Single drum, (m) Spray, (n) Fluidized bed dryer, (o) Pneumatic conveying (mostly after Nonhebel and Moss, 1971).

MAP is produced by reaction of anhydrous ammonia and phosphoric acid in batch or continuous reactors. It is then crystallized in conventional crystallizers since the partial pressure of ammonia over this acid solution is low. Crystals are centrifuged and dried below 100°C in a rotary dryer, and mother liquor is returned to the reactor238. 

Motor-driven process compressors Turbine-driven process compressors Complex multi-unit packages TDC/PLC and batch controllers Rotary dryers / filters... 

Most direct batch dryers are fluid bed types such as those which retain the batch on a screen while pneumatically fluidizing the product. Mechanically agitated or tumble rotary dryers also exist. If the product is temperature... 

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