APV Dryer Handbook - Umbc

The Spray Bed dryer is a highly specialized unit that can only produce
agglomerated powder, although the degree of agglomeration can be controlled.
Agglomerates from the Spray Bed dryer exhibit excellent characteristics. They are
very compact and show high agglomerate strength and good flowability.
CONSIDERATIONS AND CONCLUSIONS
While the agglomeration process improves the redispersion, flowability and
non-dustiness of most fine powders, it invariably decreases the bulk density.
The comparisons in Table 5 clearly show that agglomeration improves the powder
wettability and dispersibility. Individual powder particles with a mean diameter
of less than 100 micron are converted into agglomerates ranging in size from
250 to 400 micron with the re-wet method being able to produce the coarser
agglomerate. The powder bulk density will decrease from about 43 lb/ft3 (670 Kg/m3 ) to approximately 28 lbs/ft3 (450 Kg/m3 ). Use of the re-wet method
will expose the product to one additional processing step which can somewhat
affect the proteins, occasionally resulting in a slightly poorer solubility.
Since fluid bed agglomeration can be operated as an independent process, it can
be used in conjunction with existing powder producing equipment. It offers great
flexibility and ease of operation – and provides a convenient way to add
functionality, non-dustiness and value to a number of products.
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