Page 146 - Adsorption Technology & Design, Elsevier (1998)

6

Design procedures

Fixed beds are mechanically simpler than moving beds but operate in an
unsteady, and usually cyclic, manner. As a consequence, extensive com-
putation may be required to predict rigorously the amount of adsorbent
which is required in a fixed bed for a given duty. The variation of parameters
with time needs to be taken into account in formulating the design model.
Moving beds, on the other hand, may pose greater challenges in the
mechanical design rather than in the process design, since the latter would
not normally include the dimension of time. To illustrate this simplicity, the
process design of an ideal fluidized bed adsorber in which the solids are
assumed to be uniformly mixed would be similar to the design of a stirred
tank reactor. Also, the design of an adsorber with the solids in plug flow
would be similar to that for other types of countercurrent contactors. In
general, the principles of design pertaining to the adsorption steps described
in this chapter are applicable equally to the desorption steps.

6.1 DATA REQUIREMENTS

Data in five categories are required for the process and equipment design
phases of any adsorption process.

(1) Adsorbate-adsorbent thermodynamic equilibrium relationships (as
described in Chapter 3), including appropriate interaction data for multicom-
ponent systems; it is necessary initially to identify an adsorbent which is