ABSTRACT
It is a common experience of foam fractionation researchers that, in a conventional foam fractionation column, the various operating parameters have competing effects on the enrichment and recovery of a foam fractionation process (Wood and Tran, 1966; Lemlich, 1968; Timmons et al., 1995). For instance, among the two principal process control parameters (i.e., the superficial gas velocity and the bubble size), an increase in superficial gas velocity increases the flux of surface area and thus improves recovery, but at the same time it results in a higher liquid content of the foam, which reduces the enrichment. Using a smaller bubble size has similar effects on increasing the surface area flux, but also results in a wetter foam that has lower enrichment. While this type of dilemma also exists in other unit operations, for foam fractionation it is particularly complicated due to some intractable properties of the foam, and, to some extent, the lack of a mechanistic understanding of the process.
