Paddle dryer

Mechanical conveying (usually horizontal), e.g., band, tunnel, and paddle dryers... 

The most common problem with paddle dryers (and with their closely related cousins, steam-tube and indirect rotary dryers) is the... 

Figure 5. Chemidry-EO Horizontal Paddle Dryer. (Courtesy of COGEIM SpA)...

For products which need a very high standard quality level, a different version of the horizontal paddle dryer (Fig. 6) has been designed. The construction differences can be summarized as follows ... 

Figure 6. Steridry-EO Horizontal Paddle Dryer of overhung design. (Courtesy ofCOGEIMSpA)...

In the vacuum batch dryer, approximately 60% total volume is required for optimum drying result. A very simple and approximate equation can be used for the scaleup of vertical pan and horizontal paddle dryers ... 

As with the paddle dryers, these are mostly considered to be indirect dryers since heat transfer is from the jacket. If the product is a sticky, pasty material one may wish to use this design. The advantage of the pan dryer is the availability of several heated agitator designs which improve the overall heat transfer rate appreciably over a simple heated jacket the reason is the same as mentioned in the previous section on paddle dryers. As mentioned earlier, venting of the dryer is necessary to remove the evaporated vapors. 

Komline-Sanderson Corp. 100 Holland Ave. Peapack, NJ 07977 Continuous Paddle Dryers... 

FIGURE 23.16 Continuous vacuum paddle dryer (1) vapor filter (2) steam jacket (3) shaft with paddles (4) paddles (5) valves (6) shaft drive (7) shaft oscillator. 

A second aspect to consider is the mechanical stress acting on API particles in large-scale dryers, especially paddle dryers, which can lead to attrition and particle breakage (Figure 18.5). 

FIGURE 18.5 Influence of mechanical stress on drying (A) API after filtration (B) API after drying in a paddle dryer. 

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