When the process under review includes reactors or distillation columns, the PFD
review will invariably check to see whether FEHEs (Figure 25.1) and FBHEs
(Figure 25.2) are included. If not, these are likely to be documented as ideas for
evaluation. Even if they are present in the existing design, they are often documented to
evaluate whether there is an economic incentive to install additional heat exchangers, or
to modify the existing heat exchangers to increase heat recovery (see Chapter 10).