Design of Dryers

9 Plate heating system with lowered CQC-hanging trucks 

15 CQC-hanging trucks Rotary vacuum pump Lobe vacuum pump 

From the discussion in Chapter 5.2, the existence of a number of different, technically important, wet products showing extremely different drying behavior is forwarded. An attempt to adjust the drying process to best fit the produet behavior and throughput has led to a number of different dryer designs. 

---

Dust explosions usually occur in two stages a primary explosion which disturbs deposited dust followed by the second, severe, explosion of the dust thrown into the atmosphere. Any finely divided combustible solid is a potential explosion hazard. Particular care must be taken in the design of dryers, conveyors, cyclones, and storage hoppers for polymers and other combustible products or intermediates. The extensive literature on the hazard and control of dust explosions should be consulted before designing powder handling systems Field (1982), Cross and Farrer (1982), Barton (2001), and Eckhoff (2003). 

In order to aid in the design of dryers by analogy, examples of dimensions and performances of the most common types of dryers are cited in this chapter. Theory and correlation of heat and mass transfer are treated in detail elsewhere in this book, but their use in the description of drying behavior will be indicated here. 

For the experimental design of dryers, much information can be obtained from the sorption isotherm and simple tests in a drying oven. Ultimately, however, tests must be performed in a test apparatus of the same design, because only here can certain properties such as caking, damage to the product, and attainable particle size distribution be determined. 

Advances in the implication of engineering to the modeling and design of dryers under radiation were done in the 1990s. As an example, a canplete model for a multiple-zone process for drying polymer-solvent coatings has been developed by... 

Ratti, C., 1991. Design of dryers for vegetable and fruit products. PhD Thesis (in Spanish), Universidad Nacional del Sur, Bahia Blanca, Argentina. 

Drying kinetics analysis (numerical methodology such as finite element or finite difference solutions of governing equations) of the transient coupled heat and mass transfer inside the material under different boundary conditions can help determine drying time and optimal drying conditions that are essential to the design of dryers. Such analysis can greatly reduce experimental cost. 

Demonstrated examples show only a fraction of the useful functionalities Simprosys possesses. Interested readers may visit www.simprotek.com to download a free trial version of Simprosys and follow the examples in the tutorial of the software package. They will find that Simprosys is an extremely intuitive, user-friendly, and useful tool in the analysis and design of dryers and drying-related engineering calculations. 

The information in this book can be categorized as product related, equipment related, and the relationship between the two—the system of drying. For products not specifically covered, or for the design of dryers not detailed, users can select closely related applicable information to meet many needs. The user may want to pursue a subject in considerably more detail. Pertinent references, but not voluminous overwhelming bibliographies, are included at the end of each chapter. An appendix devoted to an annotated bibliography is also included. 

Moller and Pfeiffer Dryer. A multi-track tunnel dryer with concurrent air flow and heat recuperation from the hot air at the exit end. This design of dryer is well suited to heavy clay products requiring gentle initial drying. 

---