Page 102 - Adsorption Technology & Design, Elsevier (1998)

Processes and cycles 99

minimum. Additionally, heat transfer in moving bed and fluidized bed systems
is better than in fixed beds. Thus if the technical challenges of designing
adsorbents which are sufficiently rugged for moving bed and fluidized bed
processes can be overcome then not only will less inventory of adsorbent be
required but also the processes will be easier to design. In contrast, the
equipment required for a moving bed process will inevitably be more complex
and hence more expensive than fixed beds. In addition equipment will need to
be provided to cope with attrition of the adsorbent which will inevitably occur.
In order to gain the best advantages of both the fixed bed and the moving bed it
is technically and economically feasible to operate a single fixed bed in such a
way that a continuous steady state process can be simulated.

5.2 BATCH PROCESSES

Batch processes are important examples in which the adsorbent moves
relative to the walls of the containment vessel. The simplest process involves
mixing a batch of adsorbent with a batch of fluid, most commonly a liquid, as
shown in Figure 5.2. After a predetermined time the adsorbent can be

Adsorbent + Solution /

Figure 5.2 Basic equipment for the contacting of a liquid with a single batch
adsorbent.