Apropos of nothing, here's our mentor-by-literature, Neal
Anderson, in his book Practical Process Research and
Development, on foaming issues in scale-up reactors: To prepare
for a run, it is essential to review a process and examine the
detail of exactly how the operations will be carried out.
Vessels must be selected so that the reactions can be stirred at
the minimum volume of the reaction (Vmin) and so that the
reaction can be contamined (and usually stirred) at the maximum
batch volume (Vmax). Gases evolved during processing, for
instance during decarboxylation or neutralization of an acidic
stream with NaHCO3, may form foams; such reaction mixtures take
up a larger portion of the vessel volume. A defoaming agent was
added to a Lossen rearrangement to address these problems
(Figure 14.7); however, assays may be needed to detect the
presence of any defoaming agent in the product. For the safety
of operators and to minimize risk of contamination, any key
volumes should be measured without opening the vesse