
146 Foam Fractionation: Principles and Process Design
the conduit can be appreciable and must be taken into account. In addition,
it should be noted that the vented underow arrangement requires that the
surface of liquid in the feed vessel must be below the vented underow
height, meaning that feed cannot be supplied by gravity alone.
8.4 Cost Determinants of Design
Process design is an art, and therefore any process design guidance at
all must be subjective and nebulous. This is even truer for foam fraction-
ation than for most other unit operations, as there are so few commercial
foam fractionation plants that have been designed. Laboratory ...