PFB dryer

PFB dryers have been successfully used for drying of grains and seeds (e.g., peas, beans), sliced and diced vegetables,... 

Table 6.2 provides, as an example, the set of design equations for drying of sliced vegetables in a PFB dryer with relocated gas stream. Another set of equations for a spouted bed configuration obtained from experiments with wheat, barley, beet, onion, rapeseed, and carrot seeds is given in Table 6.3. Detailed information as well as relationships for other products such as sugar or pharmaceuticals can be found in a comprehensive paper by Gawrzynski and Glaser (1996).

The PFB dryer is taken as a basis. Source Glaser and Gawrzynski, 1990. 

A comparison of the PFB dryer with conventional band dryers for sliced vegetables operated under the same conditions (Table 6.4) clearly indicates better performance of the PFB dryer, which results in lower energy consumption and smaller dryer volume. 

Figure 20.38 shows the principle of a PFB dryer with periodically relocated gas stream. Hot air flows through a rotary valve-distributor that periodically interrupts the airstream and directs it to different sections of the plenum chamber below the supporting grid of a conventional fluidized bed. Air in the active chamber fluidizes that segment of the bed located above the active chamber. This fluidized segment of the bed becomes almost stagnant when the air is directed to the next chamber. In practice, because of gas... 

As compared with conventional fluid bed dryers, the PFB with periodically relocated gas stream offers the following advantages [57,58] ... 

Table 6.4 Comparison of the PFB with Band Dryers for Sliced Parsley and Celery Roots ...

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