Horizontal pans

In the second group of mixer agglomeration techniques, powders are moistened to a much lesser extent than the wet capillary state. Relatively weak powder clusters are formed. An example is the moistening, equilibration, drying and cooling sequence used to produce instantized food products. 

Specialized equipment has been developed for each of these two types of agglomeration, but some mixers are suitable for both methods. This distinction between granulation-instantizing equipment and equipment to produce larger, more dense agglomerates is somewhat arbitrary, as will be seen in the examples below. 

The horizontal pan mixer was used as a combined mixer-granulator in the early development of fertilizer granulation [3]. A typical machine is depicted in Fig. 4.1. It might be 7.5 ft (2.3 m) in diameter and 18 in. (0.5 m) deep and contain a 0.5 to 1 ton (0.5 to 0.9 Mg) batch of material. Rotation of the pan and mixing blades eccentric to the pan in opposite directions creates a constant state of agitation and, with the addition of plasticizing agent such 

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Most vibrating conveyors are essentially directional-throw units which consist of a spring-supported horizontal pan vibrated by a direct-connected eccentric arm, rotating eccentric weights, an electromag-... 

Top-feed drum filters are used for the treatment of very fast settling solids that cannot easily be kept in suspension. A drum filter may be preferable, rather than a horizontal pan or similar filter, because of its low cost, simplicity and reliability, and because of the relative ease with which it can be fitted with appropriate accessory features. A top feed drum filter incorporates multi-compartments, drainlines and a rotary valve identical to those in a conventional drum filter. The feed slurry is introduced at, or just before, top dead centre, and the cake is discharged from 90° to 180° from the feed point. The feed slurry can be distributed across the drum by sprays or a weir box, or it may be contained within a 3-sided head-box which is sealed against the moving drum at each end and across the back on the ascending filter surface. For materials which do not cake together sufficiently to be self-supporting on the drum surface, a hopper-type top feed filter may... 

A horizontal pan filter is similar in operation to a vacuum Nutsche filter. It consists of shallow pans with perforated bases, which support the filter medium (see Figure 10.15). When a series of pans is arranged around the circumference of a rotating wheel, the operation of filtering, washing, drying, and discharging can be made automatic. 

FIG. 12-54 Atypical horizontal pan vacuum dryer. (Blaw-Knox Food 6- Chemical Equipment, Inc.)... 

Performance and Cost Data for Batch Vacuum Rotary Dryers Typical performance data for horizontal pan vacuum dryers are given in Table 12-27. Size and cost data for rotary agitator units are given in Table 12-28. Data for double-cone rotating units are in Table 12-29. 

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