Temperature-maintenance schematic

Fig. 7.77 shows two schematic representations of a rectangular contact fluidizer which, in this case, also incorporates back-mixed as well as plug flow sections. Therefore, it can be utilized in much the same way as discussed before. Plug flow is achieved with baffles arranged transversely (see also Fig. 7.73). As shown, a rotary distributor disperses the wet feed evenly over the back-mixed section (dry feed and atomized binder liquid could be also used) which, in addition, is equipped with contact heating surfaces that are immersed in the fluidized bed (see also Fig. 7.74b). As shown in Fig. 7.77b, the heating panels can be easily removed for cleaning and maintenance. The supply of thermal energy is selected such that a substantial portion of the required heat is provided by the panels. Therefore, it is possible to reduce both the temperature and the amount of gas through the system significantly which is particularly important if the material to be treated is heat sensitive.

The manufacture of molecular sieve adsorbents has been reviewed by Breck > and more recently by Roberts. The steps in the process are shown schematically in Figure 1.12. A variety of different starting materials may be used. In the hydrogel process the reagents are added in soluble form as sodium silicate and sodium aluminate, whereas in the clay conversion process the alumina is added as a clay mineral, usually metakaolin. Formation of the desired zeolite depends on maintenance of the correct conditions of pH, temperature, and concentration. Seeding may be used to promote crystalliza-... 

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